I wouldnt know where to begin.
Building your own can mean big trouble. 1.) No offers. 2.) Most of the time, there are no monthly fees. Just pay up front. Ehh... 3.) The whole thing will be a giant. Two feet high and chances are it'll look not too good, either. 4.) No support. 5.) Will crash about 30% more often than a licensed comp 6.) Chasis designs. If you want a good one, it'll cost a lot and you might not get specs.
I saw my friends' and I hate it. He hates it. It doesn't run as well. If he screws anything up, he pays the price. Literally.
What about the Gamer XP
Go on the internet and look for how to build your own computer guides. i think Intel has a guide on it If you know a person who custom builds computers for a living goto him/her and you will get waht you want and will not cost $3000 like an alienware i got mine custom for $1300 and it has not crashed at all in the year i have had it:D If you build it your self or get it locally you get it upgraded. All the big name computer manufactures dont let you upgrade em. I had a HP and me tried to insert a new video card into it and we recieved the bule screen of death:eek: here are my spec p4 2.4ghz 512ram ATI Radeon 9000 128mb intel mobo 60gb Maxtor HD 1/2 tower blue case 2cd drives (1 read 1 read/write/re-write) sony floppy drive 17inch Envison flat screen crt 2.1 Altec Lansing speaker package Microsoft opcital mouse