Latitude C810 PXE boot conundrum

I just bought a used Latitude C810 that came from a corporate environment - and need a bit of assistance  in disabling a PXE boot so that I can boot from  Windows XP PRO using a single hard drive.  Right now I must have 2 hard drives installed in order to run the OS. 

  There are 2 hard drives on the machine: a 30 GB toshiba HDD  in the HDD caddy that shows in COMPUTER MANAGEMENT as the boot drive.  And a 30 GB Travelster HDD in the the HDD module bay that shows having the system files. 

  Now, at power up, the laptop boots from the 30 GB hard drive in the HDD caddy and then hands off and runs Windows XP perfectly from the 20 GB HDD in the bay module.

  I believe the Admin used the PXE boot to boot from the server - but put those boot files on the caddy HDD when the LT sold.

  Errors are:  Start up with caddy HDD removed - boot error.  Startup with module HDD removed - no operating system found.

  I want to use only the one 20 GB HDD (with Win XP OS now installed ) in the caddy, and put a cdrom drive in the module bay.

  I can't boot from floppy or CD - the PXE boot instructions are in control, and override my attempts to set the boot sequence in BIOS.

  Should I wipe NVRAM - and what keys will do that on my machine? - BIOS version is currently A03.

  How can I find out if the Win XP PRO OS installed on the modular bay drive is bootable?  I am a bit timid about getting in the situation where my OS won't boot at all - I do NOT have a recovery disc for Win XP.

  Many thanks,

   Pappy