I was able to get vmware workstation working on OBSD with few tweaks so I am pretty set on using that.
Are you using VMWare 3.x from ports, or VMWare 4.x in Linux emu? VMWare has made quite a few advancements (at least on the Windows versions I've used). Depending on your testing requirements and budget, ESX or GSX may work better for you.
1. Will such server significantly benefit from multiple processors where most applications are not threaded but rather separate processes (vmware images)?
I'm not sure if the workstation version of VMWare will provide multiple processors to the guest OS. It should help run multiple guests at once though.
I am thinking of going with a socket 939 motheboard and Athlon64 so that it will be possibe to upgrade to Athlon64 X2 dual core when it comes out in few months and switch to MP kernel if necessary although my feeling is single cpu will suffice.
Be careful, for OBSD to work with dual-core the motherboard will have to support MPBIOS, which most desktop boards don't. Search the archives for hyperthreading issues on desktop boards, the problem's the same. You may want to get a 2-way board now, then put in 1 or 2 dual-core chips as needed. (It might be interesting to see if it'd work with one single-core and one dual-core.)
