The configuration file for the bootloader (Lilo) is located on the second hard disk drive, so you can't un-plug it.
Use the Linux boot disk or the Mandrake CD to boot into Linux.
In order to make windowsXP boot by default, you will need to edit
/etc/lilo.conf
Change the Label on the
default= line to that of windowsXP (you can find the name of the label further down in the file).
To reinstall Lilo, at the command line, type: