First of all would I need a sound card to plus my headset into a self built computer?
And second of all which one should I get if I do need one?
I have a creative fatal1ty headset.
this is my computer that I want to build. http://uk.pcpartpicker.com/user/Severfeather/saved/2xuf
No. YOu Don't need one. I reccomend it for gaming IF you game with surround sound. I Use my sound card only for the optics line going into my reciever for when I play games. I have used on-board before. It works fine. I have seen issues with audio related tasks hogging cpu with on-board, but if you have an Athlon 2, you should be fine.
If you ARE going to use on-board sound, I reccommend another board. This board has 1 audio out port. My board (MSI 785GT) multiple outputs.
Many motherboards have on-board sound. The motherboard in your part list does have stereo analog outputs and an analog input which can accommodate a headset with a 3.5mm jack for sound as well as a headset with both a 3.5 plug for a mic and one for the sound. Also, if you have a USB headset, they have built-in sound processing and there are USB connections on the board and case. Either way, you're set with that motherboard without an add-on audio card.
When it comes to sound quality, that might be a different story depending on your expectations. Most sound processors on motherboards offer sound quality that's more than adequate for most people. When it's not, that's when people look for add-on PCI or PCIe sound cards.
I'd say try the motherboard's on-board sound processor. If you're not satisfied, drop some coin on a sound card. This way, if the provided sound gives you what you need, you can save the money for your next upgrade or whatever.