This site agrees http://www.cpu-upgrade.com/mb-ASRock/775V88+.html
Core 2 Duo's may be LGA 775, but that particular board doesn't support them. It's a BIOS (and possibly chipset) related thing. It doesn't have anything to do with the socket. Nothing you can do about it, unfortunately.
Feel free to try it if you wish, but I promise you it won't work.