most motherboards/processor packages come with fans, but i would recomend trying to find a higher flow fan. They usually also come with a built in ethernet (nic) card as well as a sound card. so unless your running some serious heavy sound equipment, then you should be fine with whats on the board. don't forget the little things too, like thermal paste for putting the processor on the motherboard (they come sperated). oh... and you can never have enough fans. Infact, i would actually recomend to have more exhaust fans than intake fans. Intake fans will bring in air and it will sit there and get hot. exhaust fans will suck it out, from other fans and holes in the case.

The hardest part of putting my computer together was getting all the plugs in the right slots (for buttons, lights, buzzers, the whole shebang) because i forgot to look at the direction sheet the computer came with... other than that. it's a breeze, anyone should be able to build there own computer.