Failure to boot

The most probable cause of this failure could be your boot loader (boot.ini, in the root c:\) Open it in a text editor and make sure that it looks something like this...

[boot loader]
timeout=0
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect fastdetect

Also, if the Win9x HDD has the jumper set to Master, the PC might be trying to boot from this. Change this to slave and connect up to the CD-ROM connector. This ensures that the HDD becomes the Secondary Slave (IDE2), Channel 1 as opposed to the Primary Slave (IDE1), Channel 0. The OS will look first for a bootable device in the order IDE0, 1, 2, etc... Check in BIOS to verify that the primary HDD, IDE0 is the first bootable device.

Failing all else, locate and copy the file wpa.dbl, usually in %WinDir% to a floppy while the two HDD's are connected and booted into Windows. Remove the secondary HDD and copy thefile back into %WinDir%. This file contains the mappings for the PC hardware for purposes of WPA (Windows Product Activation) and may be invoked after some hardware is removed leading to failure in booting. Before this, make sure your copy of XP is fully activated.

Did you reset the jumpers on the Maxtor drive back to single?

I do know that Western Digital drives will NOT boot if set to master when they are the only drive present.

Chas