Here's some guidelines for you to follow when choosing a motherboard.

1.) What are your plans for this computer?
2.) How much are you willing to spend?
3.) Do you want an standard ATX or microATX motherboard?
4.) How many PCI, PCI-E, and/or AGP slots do you want? You want enough to be able to install additional cards in the future.
5.) What speed PCI-E or AGP slots do you want?
6.) What type of memory do you want?
7.) How much memory do you want?
8.) Do you want SATA connections? If so, how many?
9.) How many IDE connections do you want?
10.) Do you want internal firewire connections?
11.) How many USB ports do you want?
12.) Do the chipsets matter?
13.) Does brand matter?
14.) Are you planning to upgrade the processor in the future?
15.) If you are planning to upgrade the processor in the future, what processors above the one you buy are compatible with the motherboard?
16.) Are you planning on overclocking?

Your answers to those guidelines determine the motherboard you get from the ones you listed. If your answers don't match up with one of the motherboards on that list, look for one that does.