Chuck -
A few things to check out before you buy/install the memory. First, make sure that all the slots are not already full. Reboot the server and hit F10 to enter into the BIOS (setup) of the compaq server. Compaq has excellent diags (hopefully whoever setup the server installed it). It will tell you how many slots there are and what is in each slot. In order to add memory, you may have to remove some of the existing if all the slots are full. Some of the Proliant servers have memory that must be installed in pairs. Check their website if you are not sure. Most of the newer proliant servers are nice to work on inside. Some of the older units require you to disassemble a lot of things, so take notes what goes where when you remove stuff.
Jay