SP2 slows my machine right down

Archived from groups: microsoft.public.windowsxp.help_and_support (More info?)

After several installation attempts of SP2 on my winxp home athlon xp2400 and
the lamentable performance that this causes I have discovered that prior to
the service pack my ultra DMA transfer mode was mode 5, but after the
installation it refuses to allow me to change from PIO mode only to DMA mode.
I have uninstalled the primary ide channel but to no avail and reinstalled
the drivers, changed the transfer mode to PIO mode and then back to DMA mode
as per the instructions on one of the suggestions on this site but it still
won't budge off PIO mode only. My system crawls along in this mode but was
absolutely fine pre service pack. I would revert back but as Microsoft will
obviously only support SP2 shortly I would love to slolve this problem. Any
help would be extremely gratefully received.