Building my first computer I have a few questions...

Hi my first post as well.

1. How do I know which motherboard best suits my needs. I have checked various sites and none give you advice on which MOBO you should use according to what you will be using it for.

2. What kind of price is classed as a good price to pay for a decent MOBO?

3. The two questions above apply to processors as well.

I will basically be using my computer to download occasional films and music which I will obviously be viewing and listening to plus surfing the net.
Obviously I want something decent enough to get me through the next 3-5yrs but I don't need anything for gaming, I don't play games on the PC.