Hey...you gotta do regular registry maintainence to clear out references to old DLL's etc. All the tools are out there. I use a couple different tools to sweep the registry every so often. You gotta keep an eye on the task manager for odd processes, keep TSR's to a minimum. I don't think I've ever reloaded windows except for hardware failures. I have done a recovery operation now and again for really bad problems.
If it was somebody's elses machine I might reload the OS, but not on mine baby. But then I only use Win2k (XP on dual boot) and it's extremely stable.
JohnnyB