It all comes down to what and how things are installed. I have a single XP image (moving to a W7 image this summer) for my application development, web development, and sql reporting groups that does not have any issues. Apps include Creative Suite, Visual Studio, SQL Management Tools, Office, assortment of browsers, multimedia apps, etc.
In general the usual breakdown of Windows issues is as follows:
1. Overwhelming majority is due to crappy drivers (video, sound, etc.)
2. Crappy software applications
3. Faulty hardware (memory, hard drive, etc.)
4. Actual OS bugs.