I'm building a new computer. (surprise!) This will be my first build, after my 4 yr old Dell XPS blew up and I learned the fact that all the parts for Dells are proprietary. I'm currently using a GTX 460 (768 factory oc) from my old XPS that I just bought and I'm looking for the best guts I can buy for $700 here is what I'm looking at right now.
I would also recommend a mid tower case as opposed to a full tower, but that is more personal preference as Full towers are HUGE. You also do not have a HDD chosen, nor whether you need a OS or not. So those are other factors to consider.