I thought about it a bit and realized that a laptop would be a bad idea ergonomically. I've been having wrist and elbow pain and it gets worse when I use my girlfriend's laptop.
Plus, I just spent $235 for a WorkRite keyboard tray and arm, so it would be a bit of a waste to get a laptop. The last thing that killed the deal is performance. A good desktop will always be faster than a good laptop and I really want my next PC to be pretty killer and to last a while. Would be nice to have a PC for longer than a year without feeling the need to upgrade.
Anyhow, so now the question is, do I build my own or buy from someone like Dell. If I build, I get exactly what I want and know that all parts are of good quality, plus I pay less. Buy from Dell (I get a discount since we use Dells exclusively here at work) and I get onsite support plus the latest technology (they are now offering dual core Pentium D systems) but not necessarily the best parts (Radeon 850 XT instead of Geforce 6800 Ultra for instance).
So I have a bit of research to do tonight before I'm satisfied with my answer, although I'm leaning towards building the tower and buying a Dell 2001FP flat panel or perhaps the 2005FP widescreen panel.