Quote from ArchAngel:
Average user is unlikely to notice a material difference between using a certain server config as a workstation and using a similar straight workstation config (i.e.., same processor/speed, memory, video, etc.).
Server configs often have things like higher throughput disk subsystems, dual NICs, dual processors, very large RAM footprints, etc. geared to servicing thousands of simultaneous requests. They also run the Server version of Windows that has some internal performance tweaks over the normal desktop version.
But it's unlikely the average user will see a noticable difference between a 3 GHz server (even a dual 3GHz config) with 2 GB RAM and ultrafast disks and an average 2.6-3GHz single processor workstation with 512M-1G RAM and an average disk drive.
The differences start to show when the box is pushed toward the edge of performance like when (especially for dual vs. single processors) you're trying to run a bunch of different high CPU processes simultaneously or have a lot of heavy disk/database intensive processing going on.