I would change the CPU and motherboard first. The CPU is a Bulldozer; called "Faildozer" by many, for good reasons. Tom's used one in a SBM build and it was disappointing all around. The later FX-6300 was a big improvement, especially if you're willing to overclock. If you aren't, you are likely to do as well with a hyperthreaded Intel i3 in most titles.
Second, the motherboard you have selected is not a true 900-series board, and has weak VRMs as shown on https://spreadsheets.google.com/spreadsheet/pub?key=0AgN1D79Joo7tdE9xMUFlMEVWeFhuckJEVF9aMmtpUFE&gid=2
Use that spreadsheet to help you choose a board not known for VRM issues. You'll want a true 900-series board to be certain of getting the latest interfaces through native controllers, otherwise they will either be missing, or provided by slower 3rd-party add-ons. Any "960," "980," and ASRock "970DE" boards do not have a 900-series chipset.
If you plan to overclock, you will want an aftermarket CPU cooler. I recommend a 120mm tower cooler OTHER THAN the frequently-parroted Hyper212 EVO; that one isn't bad, but costs more than its comparable (+/- 1-2C) competition (e.g. Enermax and NZXT), making it a bang/buck Loser.
Here are my PC parts
http://uk.pcpartpicker.com/p/3Gly3
CPU fan and heatsink is included cause a note below says it is reported as false info that will be corrected!(since retail box it will provide them) so you dont need to buy anything extra to ran the cpu. What i say is do not get that mobo! it is rather old and wont properly utilize or overclock the FX cpu. i would buy at least a amd970 chipset based mobo!
1) You don't need the aftermarket cpu cooler, because you may not oc the cpu at all, the MB has only 3+1 VRM, and the maximum operating temperatures of fx6100 will be 70C. You can use either HWMonitor or Core Temp to monitor the temp.
2) I recommend to get this MB Asus M5A78L-M/USB3 ( 4+1) for £44.84 http://www.amazon.co.uk/dp/B0054U7HIO/?tag=pcp0f-21 or other one Gigabyte GA-78LMT-USB3 but it has the RAM speed limit to 1333mhz only.