Dell is a very good machine to get...
But, what you should really look for is a machine that has the components that you want...
If you have the money to spent on a top of the line, fully loaded gaming machine, I would recommend either
1. Voodoo F-Class computer see them at
www.voodoopc.com
or
2. Alienware Area 51 series see them at
www.alienware.com
Both are pricey systems, $2500-4000, depending on what you would like installed in the cases... They are both well built, very nice to look at, tweaked, and good support...
Either one of these manufactures are what I would like to get, if I felt like dropping that much money on a game machine...
Personally, I just bought a VPR Matrix...
P4, 1+ gig memory, Sound Blaster Live 5.1 Platinum, Geforce 3 video w/64 meg (soon will upgrade this) 120 gig hard drive, cd/rw, dvd, flat screen monitor... It is plenty fast, runs all of my graphic intensive games, and was priced very, very reasonable ($1200 before rebates)... I am happy with it, and have room for expansion/upgrade..
If you wish to get a computer that will last longer than 1 year, before becoming obsolete (damn chip upgrades), spend a bit of time researching/listing what you want in the machine, then look for something that meets those requirements...
Good luck, and happy computing...