Yeah, I have the same problem. HP is f***ing horrible when it comes to Windows Server 2008 R2 x64 drivers. I have had no luck getting my 8100 to work with Server R2. None of the Universal Drivers seem to work.
This frustrates me to no end. I've purchased OfficeJet and LaserJet Pro products for multiple clients, and they work well on a local machine but are horrible when it comes to a server OK.
Why this company can't get their heads out their rear ends and write some decent server drivers is boggling me. Makes me want to slap my momma it makes me so mad!