LGA775 is the socket type, and tells you the broad family of CPUs you can use.
Each motherboard is set up to use a certain group of CPUs. When they want to add extra ones to the list, they release a new BIOS version.
This list of supported CPUs is for your motherboard, and a Pentium D is a dual core.
Just be aware of the BIOS versions and the motherboard revisions.
This link here, under the 'identify your product' bit, shows you how to find what BIOS version you have and what board revision (AA) you have.
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