My PC cost $450, and I do everything on it, and it works fine, but every computer is different.
To give you an Idea of what my computer has, here are its specs
AMD Athlon 2400+ (operates at 2 Ghz)
128 MB RAM (It is pretty slow, you should get at least 512 MB)
40 GB Hard Drive Standard
Additional 120 GB Maxtor Hard Drive for media
a6 MB Video Card
CD-RW Drive
Maxxtor IEEE1394 POrt
Sorry for going on and on, but I wanted to illustrate how you dont NEED a $2900 Turnkey editing system.