It's 2560 x 1440
(The 30" DELL ones are the same native resolution but the pixels are bigger on them).
I think your going to need a better GPU unless you play at lower game settings, maybe possibly a Crossfire/SLI setup but your talking about spending a fair whack of money!
From what i found around the net, a 6970 will run most games but not all at max settings e.g. Metro2033 / Crysis type games, 2x 2GB 6950 in Crossfire will work better, also some of the 6950s (Revision 1, reference) can be flashed to run at 6970, i really think your going to need to do a bit of reading or call your specific retailer and ask them for advice (somewhere like Scan who sell high end pre built systems).
I was also going to point out that Hazro do a 27" Pro series monitor for about £430 ish, the general consensus is that warranties for their consumer products are handled with the business side and in-house through the UK (also built in the UK apparently), but the issue is they don't have any warranty information outside of the standard 3 year RTB, no specifics or anything which is a bit amateur for any company.