Specifically which backup thing are you talking about? Here's the list of differences:
http://en.wikipedia.org/wiki/Windows_7_editions
Given that you're a fellow brit, you can get the Home Premium version on pre order from PC World *spit* for 45 quid, or the Professional one for 90 quid. Pretty damn good deals right there. There's no Ultimate pre order offer though so it's definitely checking if you actually need it.

It's the Backup and Restore Center I need the most.
But I'm slightly confused about the wiki entries for this module i.e as in 'Manual to local HDD or DVD only' and 'Yes'. I guess 'Yes' includes NAT drives or network related storage?
The PC World prices (wow, I never ever thought I'd say this) are pretty good.
So thanks for that (it would have been the last place I'd looked!).

Lets not give them too much credit though, it's actually a deal created by Microsoft, it's just that PC World are one of the few retailers to still have any stock left.

Leaked builds are not supported; current 7-compatible drivers have only been tested with the RC build. Additionally, compatibility drivers from Windows Update tend to be out of date, so if you got yours from there you should get the latest official ones from Nvidia.
Backup and Restore is included in all versions of Windows 7. Home Premium and lower can manually back up to a local hard drive or DVD. Professional and higher add the ability to schedule automated backups and can also back up to a networked drive.
Windows 7 isn't a repeat of Vista; only the most exotic Enterprise features are exclusive to Ultimate.

The Ultimate version of Win7 should be unnecessary for all but the 5% most advanced of private users. Go with Business, or even Home Premium should fit your needs.

Hmmm, I'm tempted...
Pre-order for £44 and wait till Oct 22nd (that's a long way off, but then again that's a damn good price).
It looks like PC World's offer is open till 9th August, so providing they still have allocated stock for the pre-order nearer that time, and considering I have 30 days use of Win 7 before activation becomes an issue. I can use this time to find out if it's truly what I want.

The Ultimate version of Win7 should be unnecessary for all but the 5% most advanced of private users. Go with Business, or even Home Premium should fit your needs.
And that would make me one of the 5%. As I need the Multilingual User Interface component. I could really do with that for XP too, but as I can't get a corporate edition of XP, I'll just have to wait for Win7 Ultimate.
I couldn't even take advantage of the pre-order as it was only good for upgrades and I need to keep my current XP without losing it to an upgrade.

Don't count on that - MS set the end date of the promotion but started with about 10 resellers, they're down to about 4 now and that's only after a few days.

I'm on Vista Ultimate because of the multi-lingual option too.
I'm using the backup functionality too, which is fine, but i think you can find several other freeware options that'll do the same job. So if you are only on ultimate because of backup, i'm not sure i'd stick with ultimate for win7.
Side note: Personally I don't want or need to upgrade to Win7. Vista is still pretty new, but I've had zero problems with it and its a huge improvement over xp. Win7 seems like it should be vista sp3, as the changes are minimal.
However, I suspect I'll be forced to upgrade, as i'm sensing vista is gonna end up like WinME.. with such a brief lifespan that it'll get skipped over by developers and soon stuff'll need win7 to work properly.
IMHO vista got crucified because the minimum system requirements they gave were rubbish, and everyone tried running it on hardware that wouldn't run it well. They could simply re-release vista sp2 with the name Windows 7 and it'd get a better reception than vista, simply because people's hardware has improved in the meantime.
(which is almost what they are doing...)
However, while vista was much better than it's reputation... ultimate is a total con. Frankly I think they should compensate ultimate owners by giving them vista for free. (maybe as an "ultimate extra" as there have been so few of those! :-( )

Don't rule it out - as a fellow brit you can get Home Premium for 45 quid from PC World if you hurry up and pre order. Definitely worth considering.

but i paid for vista a few months back. i have no particular inclination to pay again for the same thing ;-)
Unfortunately I need the multilingual features of Ultimate too... and they don't seem to have a preorder discount for ultimate. (as they seem intent on punishing people who paid a lot for a little extra).

Ah fair enough, though as I understand Windows 7 is quite an improvement. I've heard nothing but praise for it. It is a shame about the multilingual thing, maybe there will be an ultimate to ultimate upgrade deal later on.

I've heard a lot of praise too, but i've yet to work out exactly WHY it's such a great improvement. Seems more like a great marketing coup by MS, which is guess is only fair considering vista was a marketing disaster.

I'd be inclined to agree if it weren't people I knew saying it was a real improvement over Vista. I'm actually quite looking forward to it, not going to bother with the RC, I'll just wait until my proper copy arrives.