The most you'd need is a 560 Ti or it's AMD counter part (whatever that would be) but that's probably overkill, it's more based on your screen size than the games you play, could you tell us how big of a screen you plan on getting, resolution would be the best measure, I.E. 1680x1050, you can find standard display resolutions here:
http://en.wikipedia.org/wiki/Display_resolution
Also, the 2GB 560 is a bad choice, sorry missuse, but that wasn't a good suggestion, 2GB of VRAM is not going to help you without a fast enough GPU to use it, it just wont make a big enough difference to justify the price tag, the 1GB is superior for price/performance.
Disk drives can be replaced, or more can be added, are you talking about Optical DD or Hard DD?
[EDIT] I looked up reviews on that 560 you linked missuse and there are no decent reviews I can find, all I know is it's price around £240, which is simply too much for a 560 Ti, not worth it at all.
Last edited by Vox; May 24, 2011 at 12:31 AM.