Obviously there were compatibility issues in trying to use your old desktop pc as a server for FreeNAS. With many users using VMware to test FreeNAS, the FreeNAS guide shows how to install FreeNAS on ESXi. While the directions are for ESXi, it could apply to Player and Workstation too.
Unless you are a virtualization expert and have supported hardware, don't use this environment for production use. You won't be able to do some things, like run SMART tests on drives, but you should be able to kick the tires on the product.
If you like it - read the hardware stickies and see what's recommended. If you have still have questions, start a new thread with your proposed equipment list.
Good luck!