I have a problem that drives me nuts for the last week and a half.
I got two harddrives, a SATA and an IDE.
when WindowsXP is installed on the SATA the performance, as experienced when playing back movies, is bad (the movie would skip).
When the movie is played from the IDE (while windows is installed on the SATA) it works fine.
when the OS is installed on the IDE it doesn't matter where the file is played from, it works fine.
I should mention that the SATA is brand new Maxline III and gives much better performance than the 2 years old IDE according to various benchmarks.