Welcome to TSF.
Try repairing the boot loader:
Start the computer with the Windows CD.
At the
Welcome to Setup screen, press
R to select the repair option.
You will have to enter the Administrator password - if none, just press <Enter>.
The Windows installation will be detected - usually called "1" >> select that.
In the recovery console - type
bootcfg /rebuild > press <Enter>.
The drive will be scanned and you will be asked to:
Add installation to boot list? Press
Y.
Next prompt:
Enter Load Identifier: > type
Windows XP > press <Enter>.
Another prompt:
Enter OS Load options: > type
/fastdetect > press <Enter>.
Take the Windows disc out.
Type
Exit > press <Enter>.