MS.COM has a press release to look at Microsoft's accomplishment on year 2004, and things anticipated in 2005.

http://www.microsoft.com/presspass/features/2004/dec04/12-14YearReview.asp

Honestly I can only remember XPSP2 as the big thing for the year.

Year 2005 should be exciting though, with .Net framework 2.0, SQL Server 2005, VS.Net 2005, Windows Server 2003 R2, and all the wonderful things done by other divisions.