I don't game too much anymore though I did just finish COD MW2 and it look fine - performed well enough. I'm looking at moving my rig from a gaming outfit to one that will help me do some basic video editing - nothing too heavy (just rip from mini-dv, add music, , etc.) though with the occasional gaming. I was thinking of:
a) looking for another 8800 GTS 640 but they're hard to find
b) get a new video card
c) upgrade to Windows 7
I've been out of hardware for so long now, that for option b, I don't know if there are cheaper solutions out there that will allow me to get better performance. Is there? Either Radeon or GeForce line is fine with me...
That's WAY too much for 640mb 8800 GTSs. For $100 you can get an HD4850 new that is a much better card; http://www.newegg.com/Product/Product.aspx?Item=N82E168...
It would be a nice upgrade as your current card is really rather out of it's league for gaming at your resolution.
For something better that will perform well at that resolution for a while and is DX11 compatible this HD5770 would be a good choice for $153 if you can swing it; http://www.newegg.com/Product/Product.aspx?Item=N82E168...
You can use your old card in your sister's machine.
For video editing(and gaming for that matter) another 2 gigs of ram would be wise. Overclocking that processor would also be a good idea if your motherboard allows for it.