Filmosity is absolutely right, but my 2 cents: Mac! And get the whole FCP bundle. Just because Avid was first, doesn't mean they're the best. I'm a little biased though...I was a professional editor and had to learn Avid when things started shifting from film. At the time, I HATED avid. We constantly had to use "workarounds" to do stuff, and the cut lists where never completely accurate (thank god we were following with a film cut!). But those were the early days of Avid, and things do change, but I'll never get rid of that bad taste in my mouth. Besides, if FCP is good enough for Walter Murch...
Dan