do you have the installation CD, if yes, you can format

any harddisk.

boot the OS from the CD, and pretend to reinstall OS, at the step to select where to install:

delete all partitions on your old disk, and allocate a samll partition if the disk is big one, like 120 GB and above, and format the samll partition, the rest part you can allocate and format from the window system to save time. If you format the entire disk, it is very slow and costs time.