crwire wrote:
It's worth building one since you can get a better deal and you can upgrade yourself or if something is wrong you can fix it yourself
Not anymore. In the past few years it's evened out for the cost benefit of buying vs. building.
Since you say Christmas time I'd recommend waiting until then and checking out what deals Dell has. Right now if you were buying I'd recommend the Dell XPS 420. Ideally you'd want a 9xxx Nvidia video card and 3GB RAM if you're sticking with a 32bit version of Vista, if you're going for 64bit go for 4GB.
Dell's are fairly customizable in the part selection. The only reason you should build your own is if you want control over the brands of the parts that go into it.