An excerpt from a Tom's page (CPU buyers guide:http://www.tomshardware.com/forum/247939-28-buyers-guide-updated-2008Socket T (also known as socket 775 or LGA):
Not all existing LGA 775 motherboards support dual core Pentium D and Core 2 Duo processors...
This is a very good place to start as a guideline.
You can download SIW (freeware) to identify exactly the make, model and version number of your motherboard to research its CPU compatibility. I would download the standalone version to a flashdrive as it can be run from the flashdrive on any pc without installation.