I find it best to use the latest Strobe lighting tech - Yeah, it costs more, but you get a lot more speed compared to the slower, but cooler running, LED's.
Also, speed holes in the harddrive increase throughput 10fold.
It will work fine. The graphics memory sub-system is completely independant of the rest of the system.
The memory controller for your graphics memory is on your graphics card, not on your motherboard.
It's a different case if you were trying to put DDR ram into a RamBus motherboard :wink:
I nLite my XP SP2 installation (Remove drivers / apps / whatever I don't need + unattended installation) and use that at my reinstall disk if I ever need it. Takes about 15mins to do full reinstall. :lol: