Fernando!
Thank you so much for your help! However, I downloaded and integrated the 32bit Intel RST driver v11.2.0.1006 WHQL (choosing text mode and selecting "Intel(R) Mobile Express Chipset SATA AHCI Controller") and added service pack 3 (WindowsXP-KB936929-SP3-x86-ENU.exe), but when i changed the bios back to AHCI and booted to the custom xp disc, it still said, "Setup did not find any hard disk drives installed in your computer." 
What did i do wrong?
--Rachel