CPPM hard drive is an IDE where the CPDC is SATA, so there is no swapping between them. There is also a memory limitation (Max 2GB) on the CPPM, so if you were ever to upgrade to 7.6, you are limited to what applications can co-reside on the server. Any new CPDC should now be coming with 4GB standard, so there are no limitations for 7.6. Overall, the CPDC seems to be a very solid server. I haven't had any issues with them at all.