Anubis, here's the dilly on 2k.For what you want to do I would run win2k Professional. Server is mainly meant to handle more background tasks, and system services, then to actually be used as a workstation....don't get me wrong you can use it like that, but you would be better off using win2k prof. Also for the dual processor bit. the way 2k uses the 2 CPU's is in multitasking and stuff that multi-thread....I don't know too much about it, but it's not like having 2 500's and it be like a 1Ghz.
Dual Booting: I personally would setup a dual boot with WinME for compatibility with some progs. It doesn't support 2 CPU's, but as aventari said it will just use the one. Setting up the dual boot is very simple compared to NT 4.0. Just install WinME in a 1.5-2 gig partition at the BEGINNING of the drive then put in the Win2k cd and choose clean install...and Bam you're done.