I just deployed a dual 5150 dell server this week, and those things fly like nobody's bussiness. The thing has 4GB of ram and a 15k rpm system disk, and it was impressive. It's an SQL server with about 16 users at any given time, and the extrememly non techie employees were thanking me as I left the office and after I left for the speed improvement over their old dual core P4 server.
Of course, all it did was make me want a Mac Pro. I'm starting to look for a job, perhaps I can write one into my contract.
Matthew