I was looking at the downloads on MSDN for Virtual PC 2004, and found this rather odd:
Virtual PC 2004 35MB
Virtual PC 2004 Service Pack 1 Update 25MB
Virtual PC 2004 with Service Pack 1 17MB
How is it that the SP1 update is so much larger than the version that already contains Service Pack 1? Crazy, man. Craaaaaaaaaazy.