Like I said dude, that's it's always a good idea to do this kind of research before you buy something. When AMD64's first came out there was 754, 939, and 940 predominately. Of course 940 is mainly server used boards however, so the main question was ..."well what about 754 and 939?" Everytime someone asked that I always suggested they pay more for socket 939 because of dual channel and more upgradability.
It's been known for some time that AMD would basically drop support for their 754 line with the exception of the mobile processors (which I hope migrate to socket 939)
I know it sounds bad, but honestly it's one of those things, especially when buying a motherboard and CPU, the two main components of the system that you research this kind of stuff.
You could always try and sell it of course, that'd be your best bet.
But hell dual channel doesn't make THAT kind of difference anyway, 5-20% increase in performance, and 20% is pretty drastic in most cases.