Every gaming machine I've built in the last 5 years has been AMD based, all the way back to my XP 1800+. The words "Bang for the buck" continue to ring loud and clear for me. I've never benched my current system against an Intel product, but I've never been less than pleased with my system's performance.
Current specs: PC power and cooling 370 watt PS (older)
AMD Athlon 64 3500+, S939
1 gig PC 3200 DDR
80 gig Seagate HD
250 gig Maxtor HD
Leadtek GeForce 6800 GT (AGP)
Soundblaster Live! 5.1 Platinum
Asrock K8 Combo-Z motherboard (has S754 and S939, with DDR slots for each)
Sony Dual layer DVD-RW