Where can I get Dell Studio 1535 XP drivers from a creditable site? Dell does not have XP drivers listed.

http://forum.notebookreview.com/showthread.php?t=270228&page=4 ??

I assume you are downgrading from Vista, if so try this site
http://www.laptopdrivers.net/dell-studio-1535-download-vista-to-windows-xp-drivers/

Steve,
The problem you are having is that this computer was never designed with windows XP in mind. I think you have a couple options, upgrade to Windows 7 which will probably better utilize the hardware in the machine or find out the exact components: Main ones Sata hardware manufacturer and version, Network card information and Video card information and go direct to the vendor and download. Install XP using these drivers and then use Windows Update to try to get the other devices to be detected.
Good luck
RSOLY777

If there are any drivers you still can't find. In the device manager, right click on the device and select properties.
Then select the "Details" tab
Use Ctrl+c to copy the device instance ID string.
Then paste it (Ctrl+v) in your reply.

Your best source for drivers is the site of the manufacturer of the device (Intel, Broadcom, ATI, etc.).  Use the Hardware Ids string to identify the mfg.