If you fancy a trip to the registry, then you can change the slideshow timing, open regedit
and go to the following key.
Create a DWORD named "Timeout", with the value the
number of millseconds between image changes (1000
(Dec) = 1 second, 5000 = 5 seconds)
Note that the time of actually changing the image is not
included, so 1000 =1 second + time to decode the image
Back up first.
also there is a fix on kellys korner number 81 http://www.kellys-korner-xp.com/xp_tweaks.htm
hope it helps