+1 on id10t
The install disc should have a utility program to format the drive for you or just let the installer do it for you
$60 is a steal!!!
Get a nice fast 250gig HD
Max the ram
If it is about 800mhz then you should be able to run OSX 10.4.
earlier models I don't remember anymore but it should be able to handle at least OSX 10.3
OS9 is just plain ... trouble and getting hard to find software.