I built my own system...well sotra, i had mine custome built...it came with XP installed and i got all the parts I wanted, there was a little problem when i first picked it up however... they had no more 9500Pros left in the shop... this was the same time they took the 9500's off the market...he had in the only a Gforce 2 something or rather. said that he would get me a 9600pro, and i told the guy no. 9500pro is a better card... and he said ok. so i got the card a week later.
My machine below - don't remeber the price it came to, but i compared it to a dell machine simlar in spec's and saved me something like $300 - give or take.
so if you have you machine custome built it should be cheaper if you go to the smaller shops...some of them sometimes don't charge tax's..at least once they get to know you.
just make sue you get everything, most mistakes our hostest, sometimes they are not as fast as bigger dealer... sometimes they are faster.
As for buying Parts one by one... i find it a little cheaper to get a machine at a little shop and have them custom build around it. rather then buy all the parts your self.
ASUS P4S8X - P4 2.4B - 2 x 512M DDR333 - ATI 9500 Pro(Sapphire) - WD 80G HD (8M Buffer) - SAMSUNG SV0844D 8G HD - LG 16X DVD - Yamaha F1 CDRW - Iomega Zip 250 int.