I am running MyDMX on a 17" MacBook Pro with the latest BootCamp and Mac OS 10.5.8. I haven't upgraded to Snow Leopard(10.6.x) yet because I haven't upgraded to ProTools 8 yet.(BTW, ProTools 7.4 and 8 are NOT compatible with MSIE 8 for Windows) and MyDMX works fine.
Unless you have to live in the Mac environment, run BootCamp. Buy a cheap license for XP Home(should run you around $99 or less these days) and you'll do fine. DO NOT run Win7, Apple doens't have any supported softwae drivers for that OS yet. Win XP(32 bit) and Vista(32 and 64-bit) are supported.