Here is a list of processors that can use socket lga775:
There are no processors of any of the i3, i5, i7 generations that you can use.
Before you decide to upgrade your processor, you must ask the manufacturer of your motherboard what processors are supported by their bios.
An upgrade processor must be socket, bios, and chipset compatible.
This message was posted on behalf of Intel Corporation
Thank you very much to Al Hill for the information posted previously.
I just wanted to confirm the previous information as correct, in this case the best thing to do will be to get in contact with the manufacturer of the motherboard to get the list of compatible processors, or as you mentioned to get a new PC is always a good option.
Any questions, please let me know.