Re: where to start?!
ASUS P5Q PRO
You Look on the back of the power supply to determine the specifics.
I have a feeling your going to need new ram, if your computer is old than it might have ddr 400 memory which will need to be upgraded to ddr2 800 or something. That's another ~50+$, Also your harddrive 126gb? That's a small harddrive for video/photo editing, I recommend the WD 640gb which is another 85 bucks, and also you'll need a new OS Vista 64 BIT which is another 100 bucks. lol... But what i just told you is a nice computer.
CPU E8500MB Asus P5Q Pro
RamOCZ Reaper ddr2800 GPUVisiontek 4870
PSU Toughpower 700 HDD WD 640 GB