Before purchasing your motherboard, you need to have in mind what processor you would like whether it be an Intel Processor or AMD or any other brand. Different processors require different motherboards with different slots for the processor of your choice. For example, there is the Slot1 PIII CPU, P4 CPU, AMD Slot A / Socket A CPU and others.
You also need to have in mind whether or not you want integrated audio/video components. Integrated components on the motherboard make it possible for you to have a "built in" sound card and/or "built in" video card so that you are not required to buy a seperate card for video and audio. If you're going this route, you have to make sure your motherboard has these built in components. If not, you will have to buy a video and/or sound card seperately so that you can have audio and video.