I purchased and am happy with a Dell 6000 when they were running one of the $700 off $1500 deals. I'll just mention some of the choices I made, though your priorities may be different:
-good battery life, 4hrs plus, on a 9 cell Dell
-Pentium M (Centrino) processor. you'll see P4s offered at what seem attractive prices, but the centrino runs cooler and longer on battery. also, the processor speeds quoted for Pentium M units understate their speed vis a vis P4s
-WSXGA+ (the mid-level upgrade) screen is great for charts
-Dell has the Bios set such that the cooling fan is always running, but you can use fangui (free program) to set the fan to run only when the processor reaches certain temps (still well within the safe zone) and the 6000 is very quiet. My fan typically runs only a few times per hour and then only for 15 seconds or so.
-15.5 wide view screen has plenty of real estate for when I trade and travel. At home I just connect to an LCD. I considered a 17", but decided the extra drain on the battery was not worth it.
- integrated graphics. Intel recently upgraded their integrated graphics and it works just as well for my trading as did the more expensive, power slurping, and heat generating dedicated cards I previously used.
There are better machines out there, but I couldn't find one anywhere near as good at the price when Dell ran one of these specials.