Al has a good point there,

If you don't know the MoBo then tell us the make and model of computer, what processor it has and the RAM type/capacity ( <control panel> then <system> will get most of that) and the BIOS (usually comes up just as you boot, or go into settings and you will see.........something like Award, AMI or whatever)

This is particularly important with old brand name (ex-corporate) machines, as they tend to have custom MoBos, BIOS and the rest.

I guess that I am fairly confident with Compaq, Digital, HP, IBM and Dell; but the specs change so much it would help.

Cheers