No way that this machine will support 10,000 concurrent users, IMHO. Low on diskspace, no separate spindles for the DB and the logfiles, etc. This machine might do for a proof of concept, but not for production.
I work in one company that have more than 50.000 users, 10.000 groups and 100.000 computer accounts. Yup. Have 22 different sites and a lot of more objects.
We have two domain controller per site. Each one have 4 x 36GB array disk each, 2gb ram.
Don’t tell me that please…
The database is no more than 15GB