Hard disk -
Graphics card -
Memory (Ram) -
DVD drive -
Floppy disc -
Network card (if not with motherboard) -
Sound card (if not with motherboard) –
You will also need a heatsink and fan if you don't buy a retail boxed processor. Oh yeah, and a PC case and a Power Supply unit (if the case doesn't come with one as standard, 95% of them do).
Some motherboards have on-board graphics which, while generally of questionable quality and useless for gaming,, are good if you're on a tight budget and you can always add a separate card later.
Virtually all motherboards these days come with an onboard network port and onboard sound. Quite a few are now coming with onboard Firewire as well and 7.1 quality sound. Some people argue that the onboard peripherials don't perform as well as separate cards but most people will be hard pushed to spot any performance gain from a separate card.
and another thing, i know certain things need to match, im probs getting AMD stuff, so what things do i need to buy that will match??
Well a visit to Crucial.com with the motherboard model number and brand name will give you a list of memory sticks that your computer will like. You can also buy graphics cards there as well.
Apart from that, the only other things that need matching are:
1) Processor type to motherboard type; that is to say, an Athlon XP (which is a Socket A/462 chip) processor will never fit on a Pentium 4 board and vice-versa.
2) If your choice of board supports DDR memory then you'll generally want to go with PC3200/DDR400 memory. There is DDR500 available but most DDR boards won't take it so don't buy it unless Crucial's site tells you otherwise.
3) The Front Side Bus (FSB) speed of your processor is related to the speed of the memory. If, for argument's sake, you buy an Athlon XP 2400, this has a FSB of 266Mhz, then even if you buy DDR400, iit'll run at the slower speed as the processor is the slowest link. Boards with DDR2 memory don't suffer from this.