Some of the background tasks such as the Performance Monitor don't work because it depends on the continuous logging performed by the Task Scheduler. But the Performance Analyzer works like a charm. Also, since the defragger now works in the background, it will also not function. But personally I have found neither of these functions all that useful, and disabling the Task Scheduler got rid of so many annoying quirks, that it was probably the single best system tweak that I did. This has been covered in this forum in the past, so let me know if you have trouble disabling it.
J.A. Coutts