Hello Walt,
Based on your system chipset the following processors are the ones listed as compatible:
http://ark.intel.com/products/27733/Intel-915G-Graphics-and-Memory-Controller
To find out whether or not your system can be upgraded with a different processor, both, the BIOS and board will need to support it. For this reason, I would suggest checking with the system builder to confirm if those units are fully compatible with your system.
You may want to call them at 1-877-293-1197
Regards,