No decent software in Windows has required a system restart for quite some time.
I guess anti-virus software is not decent. Neither are windows updates. Neither sql server, visual studio, .NET framework... should I go on?
There are plenty of problems with the registry, but slowdowns after 36 hours is one of them. Uptime for Windows 2000 or XP can easily be months if you don't want to update your drivers.
Uptime isn't months, not because of blue screens but because of slowdowns. You answered yourself nicely on this one.
I may sound like MS bashing, but think about it for one minute: The bigest software company in the world, with unlimited (for all practical purposes) money and resources, and 20 years experience on desktop OS, cannot give us an OS that does not need reboot every week (for performance reasons at least)?
Are we happy with an OS written over a period of 5 years which costs as much as the computer it is run on (Vista Ultimate)?
/end offtopic