If you've got the money I would suggest a dual-core dual-proc system. That's only if you've got a ton of money though. If not, just go with a high end dual core cpu. 2 gigs would be nice, but one gig will get you through just fine.
The video card is really not that important unless you start doing a lot of 3D stuff. A 6600GT should have you set you up for a very good while for anything besides pure 3d rendering. You could even easily get by on a lower model card, but I'm not sure that the price/performance ratio would make it worth it.
Beyond that I highly recommend getting at least one 10k RPM raptor hard drive. They get way better performance than most other hard drives (though a few new 7200s are coming close in a couple areas). With the hard drive being one of the slowest components of a computer, I can't believe that more people (notably "enthusiasts") don't have one of these, though MANY do. The only draw is that a single raptor is only 74gb. Unless you are dealing with a very uncompressed video format however, this should be enough to have quite a few projects in rotation at once. Obviously, you'd probably need a storage hard drive, which is easily enough acquired. You could even slap two raptors in Raid-0 to form a 128gb hard drive that is even faster, if you are concerned about the space. As long as you transfer your projects over to the slower HDD once you are good and done with them, it really shouldnt be a problem though.
I've done video editing at a small studio for a couple of years, and that is my advice to you.
BTW, between an extra gig of ram or a raptor HDD, I would take the Raptor any day. Well, unless its a server or some stuff like that......