Purchase from a store close to you. Stuffing Computer parts in a box for shipping is time consuming and expensive.
Min
Pentium 4 running at 2.5 or higher
Motherboard that CAN take 1 meg or More of RAM
Windows XP home
USB 2.0 High Speed
Firewire
Power supply 400 Watts - 450 Watts
512 k of RAM installed
Hard drive - 100 Gig - Video files are large
DVD burner - they are so cheap now and they still do CD's
Sound Card - Creative Audigy 2
Video card - Thats a tough one - todays card will serve well for Media systems, let your pocket book decide
Monitor - Flat panel - the thin one, CTR's a so BIG in back
Software
Start with the stuff that comes with the machine, and upgrade/purchase as you see a need in the area you use the most.