According to many reliable news sites, and the microsoft press release, it was about %10 of the win2k source code, nothing major was in that code.
I personally havent seen it, and highly suggest that none of you look at it either, it is _VERY_ dangerous for a programmer to look at commercial leaked source code.
If you are a programmer and you look at the win2k code, good luck ever getting a commercial job. You will be considered "tainted" (microsoft can claim something you wrote is using or otherwise based off of their source. Nasty bussiness that.