When they get the PRO rendercow situation worked out, XP and 2000 (with 2000 being the best IMHO) are your ideal choices as far as OS's go. HOWEVER, if you're never going to use it for anything else and the systems already have 98 or ME them, just use those. That's one of (the many) nice thing about being on a PC platform ... rendercows could care less which OS you're using.