My favorite boot camp experience was installing the latest version (whatever came with snow leopard) on my parents' iMac and discovering that the realtek audio drivers thought the microphone jack was the headphone jack and the headphone jack was the microphone jack. (This happened in both XP and Vista.) On my MacBook Pro, I had to role back the Sigmatel audio because, when I left the machine on for a while, the audio would become more and more static-y.
It seems like with every iteration of Boot Camp, I need to selectively role back a number of horrendous drivers to get full functionality, then install mobility-modded graphics drivers because the included ones are about a year out of date.