I myself have been doing some research on building a new Core 2 Duo system that will work with Linux. So far, I've found that:
The newer kernels support the CPU options.
Realtek onboard LAN controllers don't work.
Realtek onboard sound can be a pain to setup.
Intel boards arn't overclockable.
Intel boards have linux support.
Intel P965 chipsets don't nativelly support IDE.
SATA burners arn't really a option right now, too expensive and unreliable.
Boards that support DDR2-800 only support upto 2 IDE devices.
Most boards that have everything you need are really expensive.
Nvidia chipsets seem to work best.
There are other options that allow you to use older IDE drives, such as external enclosures.
A complete list of Core 2 Duo supported boards can be found here
So, in short, if you want to use the LAN,Sound, or IDE parts of a board in Linux, don't get that one.
Have a look at ASUS P5N32-E (nvidia chipset) if you really must have Asus. Otherwise, look at the mobo list and see which works best for you and Linux. If you don't want to overclock, have alook at the Intel boards.