Can I use a DDR2 PC2-4200 registered ECC 1GB on my workstation xw4200?
!!:no: Your system supports only DDR2 Unbuffered ECC and Non-ECC memory.
Your workstation supports a max memory of 4GB. It has 4 slots and max per slot it takes is 1GB. You can find compatible in the following link - Memory for for HP Workstation xw4200
Note: Do not mix ECC and Non-ECC memory and install the memory in pairs.