I think it's pretty clear guys that he just wants to buy it and be done with it. Building isn't for everyone, especially if you have other (time-consuming) concerns. Though I agree, he could do much better building on his own
With that said though, I suggest this Gateway computer:
It's a very solid system for what you will be using it for. Comes with a 17" CRT monitor, keyboard, mouse, and I think 2 speakers with small sub. 512 ram, 2.93ghz P4, 80GB sata hd. Should definitely meet your needs. It is $599.99 shipped.
There was a lower model for $100 less with just 256mb ram less. I was thinking you could buy that and pop in the extra 256 ram yourself, because you definitely want 512. That takes all of 5 mintues to do, depending how easy the case door is to get off. However, they charge $100 to ship a desktop, so you may as well go with the already upgraded model and get free shipping. Only costs $.01 for the extra ram that way