I wouldn't buy a comp for video editing from someone like Dell personally. Big name companies PC's are often lacking somewhere, although Dell's are maybe better than a lot of other big companies for this. You'll get a lot less bang for your buck too. I think on your budget you might get something more specific towards a good media PC. I know of plenty such specialised retailers here in UK, but in US

It would probably be a good idea to visit some US based audio/video forums and check out sites hosted by the major audio/video magazines in the US. See what recomendations for computer retailers they have.

Alternatively, if your not wanting to build yourself, a good solution might be to get the specs for your system and have a computer store build it for you. I know you say you don't have much time but, that might reflect in what you get for your money. I built a pretty darn good Dual CPU audio workstation about a year ago for about £1500 and it's still pretty darn good by today's standards. Given that was a year ago and parts are cheaper in the US, you might be able to have someone build something like this for you.