Oops, reading that does seem rather ambiguous, sorry. I'm only upgrading the GPU and I want to buy W7 as well (the copy i have right now isn't fully functional). I put the PSU in there cause the template told me to, and the wattage is important when buying a GPU, right?
edit: Yeah, I really liked the card I had, but it had some major heat issues and it would cause my computer to crash a lot and it's too late to RMA now.
I took it out and have been using the Intel graphics from my i5 2400 cpu, and it hasn't crashed for a few weeks.