Be VERY careful with Compaq ...

It is one of the few PC's that are built using proprietory brand parts.
You need to look for exact matching memory.

The BIOS on these machines is special too .. and it even (usually) has a tiny Partition of its own on the Hard-drive .. and its own special version of the O.S.

You cant just stick stuff in Compaqs and expect it to work.

Cheers!