The limiting factor is going to be more of which LGA775 Processor supports both.
Most 775 CPU's are 32-bit, with only a few of the later model and server chips being 64 bit. In order to dual boot you are going to need a CPU that is using a 64bit architecture.
Once you have a CPU, you can look at which boards support that specific CPU, but ost MB's that are 775, are going to have BIOS updates to support almost all 775 CPUs.