I edit video on Premiere Pro (which is a pretty resource greedy bit of software) and, on an i7 machine with 8 gig of RAM I rarely have problems that a bit of pre-rendering of effects can't fix. I have run PrPro on an early machine with a basic Pentium 3 and 4 gig of RAM without many problems.
However, an issue for you that I can see is your HDD storage. I just checked a recent project of mine and, for a 12 minute video with a bit over an hour of rushes and I had over 20gig of storage used. That'll fill you disk drive pretty quickly with one 40 and 80 gig drives. As a comparison I have an external 2 Terrabyte drive that cost me about $100.
The pessimist sees the glass as half empty. The optimist sees it as half full. The realist just drains the darn thing and gets a refill!