I have had two mice that I really like, a Microsoft IntelliMouse Pro (I think it was, don't remember very well - corded, ball, PS/2), and a Logitech MX700 (in a Cordless Desktop MX combo pack with a keyboard I think is equally awesome - there was a bluetooth version of it as well but I had the earlier proprietary RF version).
After the MX700 broke so thoroughly that my stubbornness to use it anyway wasn't enough I had a couple of cheap-o mice (by A4 Tech and Acrox, I think), after that I bought a Microsoft Natural Wireless Laser Mouse 6000 which is awesome in its design (except a few millimetres too high as I can barely lift my hand between the desk and keyboard/mouse drawer).
The biggest fault with the 6000 was the wheel, the steps aren't distinct enough and the wheel is made of a softer rubber that sticks to the plasic around it. This one is the only one that's still available for purchase.
The MX700 is damn close to perfect but is no longer available and the drivers don't work with Windows 7 x64 (or Vista for that matter, maybe 32-bit versions but that's a moot point), I'd try an MX518 if it wasn't wired (looks like the same mold).
The IntelliMouse Pro is wired, has a ball, and also is no longer available.
What I want is an ergonomic, wireless mouse, with not too many buttons (right, left, clickwheel and two thumb buttons, ideally), and a wheel with pretty distinct steps.
Based on these statements, what does the GOG hivemind recommend?
Edit: For those that don't know the mice I'm talking about, images are attached.

I don't necessarily recommend this mouse as I don't own one but . . . had to add it just for cyborg look . . . =)
video

I have tried several mice, but I always go back to my Logitech G9. I highly recommend it and the newer G9X model.

the G9 does seem a great mouse from the little I've used it at a mate's place. I'll end up getting one of those if & when my MX500 ever dies

i always get the cheapest i can find in the store and i am usually satisfied with the result.

I agree with Miaghstir, I also need a new high-res sleek mouse to better my noobpwnage in Starcraft II :P
I've heard good things about Razer, and I think they've just recently released a new model.

I just got a Razer, just plugged it in five minutes ago, and this is the first time I've owned a nice mouse. It is smooth as hell, and comfortable to hold. It is the best mouse I have ever held. I got the $80 Imperator.

That Cyborg thingie looks like a bitch to clean when it's been used for a while.
As for the G9(x), disregarding the fact that it's wired, how distinct are the scroll steps in "precision" mode?
Also, I don't really care about resolution or how fast acceleration it can handle or whatever, just about anything made today should fit me nicely in that regard.
I still use the crapmice by A4 and Acrox so anything is an improvement really, I'd rather pay a bit more for something decent, than a bit less for something I will regret. The 6000 started getting troubles much too soon, and cost 60€ (then I fiddled with it to see if I could fix it myself, breaking the "don't open" seals, and lost a spring, so the warranty's pretty much gone), I'd still use it if the wheel was made from a harder rubber.

Generally I find Logitech to be by far the best mouse manufacturer. It's just a question of picking one that suits you. My LX 3 has all you're asking for, minus the fact that it's cabled. It doesn't have side buttons as such. But the mouse wheel has a rebindable horizontal scroll function so that takes care of that. I have it assigned to [ & ] then bind those things to useful stuff in game.
What not to get:
Microsoft - solid drivers, but the mice themselves are built out of random crap they find in a scrapyard (like the 1st gen 360 was).
Razer - the opposite. Solid hardware but the drivers are actually a lot worse than the basic shit you get with Windows. EDIT: Oh, and they never, ever update that crap either. Seriously avoid.
Razer/MS hybrid mouse - worst of both worlds.

For wireless mice, Best Buy seems to have pretty good deals, if you're just looking for an average one.
[url=http://www.bestbuy.com/site/olspage.jsp?id=pcat17080&type=page&qp=crootcategoryid%23%23-1%23%23-1~~q70726f63657373696e6774696d653a3e313930302d30312d3031~~cabcat0500000%23%230%23%2311a~~cabcat0513000%23%230%23%2324~~cabcat0513001%23%230%23%23i~~nf396||4f6e2053616c65&sc=abComputerSP&sp=-bestsellingsort+skuid&usc=abcat0500000]http://www.bestbuy.com/site/olspage.jsp?id=pcat17080&type=page&qp=crootcategoryid%23%23-1%23%23-1~~q70726f63657373696e6774696d653a3e313930302d30312d3031~~cabcat0500000%23%230%23%2311a~~cabcat0513000%23%230%23%2324~~cabcat0513001%23%230%23%23i~~nf396||4f6e2053616c65&sc=abComputerSP&sp=-bestsellingsort+skuid&usc=abcat0500000[/url]
As for myself, I had some bad experiences with wireless so now I have wired. I don't even care that I'll have to wrap up my cord when I take it places; reliability is higher than convenience in my book.

The wheel is made of hard silver colour plastic and black rubber like stripe. It feels very good using it.
The wheel can be used in two modes. One smooth, where it feels like it has no "steps";one with steps. The steps are very distinct, without turning into a fight to turn the wheel. I am fully satisfied with it.
As for the "performance" numbers, I don't care for them either. The older model I have (the non x) you can set the dpi up to 3600 IIRC. The new one a couple of thousand more. I have it set at 2600 all the time (24" monitor 1920x1200) and it feels perfect for my taste. In the past I had it at 1800 which also feels good for desktop uses.
Some time ago I had issues, which ended up being a specific version of driver (long gone now). I thought it was the mouse, so I tried 2-3 different mice over the last few months. Good mice too.
None of which felt natural and good enough even after weeks of trying them (each). So I decided to give another go to my old G9, just in case, downloaded the newest drivers and it was like new. Love it.
It comes with two grips, one smooth and hard (for gaming) and one softer (still pretty hard) and almost velvety like (very difficult to explain) for comfortable Windows etc experience. I use the latter one all the time. It might be a tiny bit more slipper in the hand, but it feels better to me. Totally subjective of course.
Oh, it also has weights, which look like small round batteries. I thought (when I first bought it) I would like it heavy, as I did with the MS Sidewinder (the first one, horrible comforts), but boy was I wrong. I now have no weights in it and I prefer it this way.
The new G9x model has some differences, the side buttons are in slightly different position and the mouse has one or two extra buttons, it also has higher DPI and other numbers. If my G9 ever dies, I will 90% go for the G9x.
Yes, they are not wireless, but, from my experience, if you go to high DPI, 1600+, you don't find yourself to move the mouse enough to have the usual problems with cables, plus the cable for the G9x is very light (though strong).

If they're not causing you any problems in any games then I'd say keep them. But when I can't use the right mouse button in some games because the drivers are that awful, I'd call those shitty drivers.

Ouch. What games have you noticed that in? That would be a catastrophe in StarCraft II!

Any reason Razer won't work with standard windows drivers?