you'll find most of us prefer AMD's line of processor... simply because they offer a considerably better value (price/performance). i guess the advantage of an intel chip would be it's lower heat output.
after you decide which way you want to go there, you'll need to decide what motherboard you wanna buy. now when a company makes a motherboard, they base it off a chipset designed by yet another company. chipset people include VIA, SIS, AMD, and Intel. the latter two only make chipsets for their brand of processors, understandably. i think it'd be safe to say that VIA chipsets are just a little more costly but offer very good performance. SIS and AMD chipsets are a little more on the budget side, while Intel chipsets are a good choice if you're building a Pentium machine. different chipsets will have different features and use different types of memory.
once you find a chipset you like, you then go about finding a brand motherboard. when you pick a motherboard manufacturer, you have to look at past reliability, extra features you may/may not use, future upgradeability, and price. there are tons of good brands... like Abit, Asus, Gigabyte, Epox, Shuttle, MSI, and more.
that's all for now. }:>