If you can't wait until the next workstation release of Windows (Longhorn), then convert Windows 2003 Server into a workstation! This article goes step-by-step in great detail with screenshots about what exactly you need to do.
Apparently Windows Server 2003 is better on memory management, security, and stability. So the use of Win2k3 as a workstation has been making the rounds among some developers lately. Maybe I'll try it when I get some downtime at work.