Hmm well the game doesn't need anything super amazing from my short game time experiences, my little netbook with an ION 2 gpu runs the game pretty smoothly it seems.
Just about any card with dx 10 capabilities would be good enough probably, as far as more long term upgrades you'd want to go with one that supports dx 11 I would think, however which you pick is up to you and your budget. I personally love my radeon 4890...
UPS 3 DAYS $13.16
Order Total $310.10
Easy core unlock on the CPU, with the ASRock motherboard, which now turns it into a Phenom II x4. Two clicks on the BIOS, and it's running 4-cores at 3.78, and scores a 7.4 on the Experience Index. For this price, that's amazing - the processor becomes a black edition Deneb (w/out the L3 cache). The i7 920 is a 7.4 stock and it is WAY more costly.....do the math.....
I'm going to go to the local computer guy and the electronics market in Seoul today. I've been avoiding upgrading my computer because I will need to haggle and shop using Korean (not my native language LOL). It will be my first try. Wish me luck.
I'm doing it all for Xsyon, so however this game turns out, at least it's inspiring me to take on new challenges in RL.