|Is the computer currently running Win98 or something else?|
Before you go wiping the existing Windows installation I suggest you try to clean up the files, which may speed things up.
Conversely, if you are used to a newer computer the Win98 rig may be running as fast as it is capable of.
The link below is for the HP specs on that model. It indicates it came with 256MB of RAM, which should be enough to run Win98 SE, which originally came on it.
What type of media did you receive for the restore set?
Try downloading and using Ccleaner Slim - cleaner module. Get it at the link below.