im using mac os x tiguer 10.4.11 on my old pc for months...

my old pc specs:

P4 3200mhz

motherboard asrock

grafic card Nvidia Gforce 7600GT

2x 160GB ( 1 sata + 1 ide )

soundcard onboard (AC97)

everithing runs fine and i use logic pro 8.1 + reason 4.01 + reaktor 5

but for professional audio use i recomend a firewire sound card , becouse i get overload and midi/audio out of sync sometimes in logic , other softwares run fine but logic its more heavy for the soundcard

i prefer to use hackintosh in my old machine than XP , xp is more heavy

hackintosh runs smooth and very fast (even the net is faster)