any SSDs from the market which is backwards compatible to S-ATA Gen2 should rund fine.
Some of these Workstations were delivered with Intel 320 Series drives back in those days.
These are guaranteed to work because they are from HP (at least their firmware).
A3D25AA (128 GB)
A3D25AT (128 GB)
A3D26AA (256 GB)
A3D26AT (256 GB)
Besides the drive, the kit also contains a bracket (the famous BlindMate, toolless version) and two cables.