I had no success with using nLite to slipstream SATA drivers into the XP installation CD, but "WinFuture XP-iso Builder" worked perfectly for me.
I started by upgrading the BIOS to v1.0D in Vista, then downloaded all the XP drivers from the links above and burnt them to CD.
I installed the drivers immediately after loading Win XP SP2 (32bit) and all works very much better than with the pre-installed Vista Basic. The machine is so much faster its unrecognisable.
While installing XP, I blew away all 3 of the preinstallation partitions and created a single partition of 150GB. I now seem to have about 50GB more free space than before.
re the user with the sound problems, you need to ensure you load the UAA driver and you should have no problems. I also used the latest version of the drivers rather than the exact versions listed above.