ati here.. I have 3 ati cards in use atm with no problems, have owned 6, and have bought about 10 total for other peoples pc's including mine. never had a problem except the time i broke the heatsink clip on one. i have only ever had one nvidia, a geforce2 MX400
kinda the same with amd/intell. first computer was an intel PII450MX and all the rest (like 15 that I have built for me and others..) are amd based..
if you think the x1800xt is good wait till Q1/2 next year when the ATi R580 chip is released
Rumor has it that one card is twice as fast as 2 nvidia 7800GTX in SLI mode..