Dont defrag every night.. that moves your files around by repetition and will mess you up.. Try using a defrag by diskeeper (not XP) and only run once per week... if you are NTSF then only once a month or longer.

Processing files from two HD's will cause bottle necking.. you are reading, processing, and putting back on the HD in order to process information from another HD (the source program).

So put your swap file on the same HD as the PIXL and also make sure the HD's are on the IDE bus on the mother board, not on a PCI card.

Let me know how that stuff is working.
Good Luck.