You only get Mechwarrior 4: Mercenaries, which is a standalone expansion for the base game, Mechwarrior 4: Vengeance.

I wish I could say that, the problem is, I haven't actually seen it yet. I installed it, then I launched it, then it crashed before it ever fully opened, so I re-launched it, then it updated and now I'm waiting for it to actually open up....
... and still waiting
... oh look, there's something on my task bar... nope, still not fully launched, must be a teaser
... well, there is something resembling the borders of an actual application on my screen now and there is an "OK" button to be pressed, but it doesn't say what I am OK-ing and I can still see my browser through the application
... well, I clicked "OK" but nothing seems to be happening... no, wait! I think it actually loaded. It did!
.. Okay, time to try downloading something... aw crap, forgot to forward ports... WTF, now my port forwarding isn't working!
This sucks, I'm going back to playing with my new Ubuntu!

5 hours to download! Might as well let MTX continue trying to do its thing, especially seeing as I now can't seem to exit the program gracefully.

EDIT: the ever-tireless Peron has now uploaded all three parts in a single split archive right here. Download that rather than the ones below if you don't have any of the MTX files downloaded yet.
-------------------------------------------------------------------------
MOAR links thanks to Peron.
Main file:
http://www.filefront.com/16321427/mechwarrior4mercenaries.all.to.51.03.01.0017.zip.001
http://www.filefront.com/16321575/mechwarrior4mercenaries.all.to.51.03.01.0017.zip.002
http://www.filefront.com/16321455/mechwarrior4mercenaries.all.to.51.03.01.0017.zip.003
http://www.filefront.com/16321351/mechwarrior4mercenaries.all.to.51.03.01.0017.zip.004
First and second patches:
http://www.filefront.com/16321561/MechPatch.rar/
Shove them all into MTX's temp>games folder, run MTX, and pray. ;)
EDIT: note that you should also keep copies of these before trying the install process because MTX sometimes devours files and starts over.

515 minutes until download is complete? Guess I'll let this thing run overnight...

While I'm willing to try the release, definitely, MTX is a very problematic platform. They shouldn't rig their releases with this piece of problematic crap.

im being asked to insert M4 cd...did i miss something?

sorry for the double post was blatantly obvious tho :P

Thinking about it, this would probably be a WAY better free release if it was made by GOG. Too bad it wasn't.

hell I would of paid 6.99 or 9.99 for MechWarrior4 in its full glory but i suppose this will do.

So, what, it's a year of waiting and a buggy bit of client software to get a third of the game we were hoping for?

So because the server is down I can't even attempt to install the game despite having it fully downloaded, and extracting the files manually makes the game demand the CD. This is just brilliant.
Let's not release the game files with standalone installers, no no, let's force everyone to use the buggiest, most horrid excuse for a client anyone has ever seen!
This release has all the mechs and so forth (a whopping 111 of them), it only lacks the non-Mercenaries campaigns. Why they have done it this way is not clear.

Is the merc's campaign particularly good? The campaign is the main reason I play games like that

I'm facing the same problem. A stand alone installer with an online overlay for the game to allow for community options would have been incredibly more efficient.
They seen to fail at noticing the current state of DRM problems. Adding theirs to supposedly free stuff doesn't make sense.