you have a more complicated upgrade. you have lidless cpus the upgrade is harder to do.you need nylon washers to keep the heat sink from crushing the pins in the cpu socket. look around for 2009 dual cpu upgrade on the site. also the cpus are more costly.
Thanks for the info, Philip. Based on what you've said...I think I'm just going to save my money for a new machine. My existing 2009 MPro will go into service as a network render slave.