Macs can't be beat for graphics work, but I'll take the upgradeable hardware versatility of a Microsoft based machines any day. XP is a great OS and easily defended with free software and a bit of common sense.
Mac's are way over-priced for what you get and apart from their notebooks, ugly as sin.

Vista is the slowest most power hungry OS ever released [forget it for gaming]. I'd like to run a duel boot XP / Linux OS, if Linux ever gets a [genuinely] user friendly version together.