No need for parallel computing all cores are already used.
Core one: For the OS
Core two: Anti-virus
Core three: Anti-Spyware / Windows Defender
Core four: Firewall
Core five: Windows update notifications and installations
Core six: Windows Genuine advantage checks
Core seven: Eye Candy (Vista) with XP you get a bonus CPU
Core eight: What ever the user wants to run, except when you get a virus, then
you have to share it with the SPAM bot.
Guess we will be waiting for 16 core CPU's.
Oh and don't start me on memory requirements :-)