I want to install a second hard drive in my computer. I need to know if my motherboard can handle a 120gig drive. I am having trouble finding out what kind of board it it. I have a compaq presario desktop 5BW177. How do I find out what kind of board it is, and if I can install a drive that large. Thanks for any help.

Go to Compaq, find the support and then mail them. They have been quite helpful to me a couple of times. They probably know that their support pages sucks.
Then you can always use a drive that size anyway provided that it's ok to you having an extra layer between the drive and BIOS. Extra layer - in this case a special driver from the harddrive manufacturer. I've been using large drives together with different laptops this way. (IBM drives and their driver)

Go large!