powersupply is the most important to power your system and make sure your comp wont fry, however has next to 0 affect on the actual performance of your rig unless your doing extreme OC or your under the volt limit on the rail... for this reason i always recommend seasonic or corsair PSU, they use single rail for more volts and are overspeced on watts, if your using a single video card pick up a 600 or 650 corsair powesupply you cant go wrong, unless you want two video cards

no thanks

this is largely up to your resolution, a 5850 at ~1020 x 720 i guarantee you will run SOW max it will run anything max with a good CPU ect, pay attention to your screen res... ie multiply the two numbers if you have a 1600 x 1200 screen tats 1.92 million pixels, a 5850 would likely run sow very well at that resolution but likely wouldnt max it out.. however if you run a 2560 x 1600 screen now your pushing 4+ million pixels now you'll want more power, generally if your running 4 million pixels or over youll want a high end nvidia 480 / or a nw ati 6870 coming out less than two months.. if your under 2 million pixels the current ati cards should do fine or a nvidia 460 should also do beautifully, also the processor is very important in this case, i would recommend quad core definitely for SOW, if you want more CPU power dont buy a high end CPU you'll get more value for the money OC.. if you can't OC.. buy a pre-OC system.. easy even with the premium you'll pay to have a system built if its OC youll more than make that money back.. not sure if ibuypower does OCs, but lots of custom built companies will oc for you and even guarantee the OC and replace anything if it fry's check the warranty before purchase!!..(http://www.digitalstormonline.com/ they will OC a prebuilt for you and its absolutely guaranteed, if it blows they;; replace.. however its highly unlikely occurrence with current tech, and adequate cooling failed OCs are very rare.. how rare.. well with air cooling and a corsair PSU, and good motherboard less than 1% and that 1%)) however if you can I highly highly highly recommend building your own computer and OC, get a low end I7 920 or possibly something in the 800 line, with a decent motherboard its sooooo easy to OC, you'll get 3.4ghz easy just with stock cooler more than that custom air cooler also easy to use, the reason id recommend the I7 for first time OC is because its soooo fool proof, its basically impossible to blow anything up as long as your PSU and motherboard is decent, and its a really easy OC, a few clicks in BIOS and done, never touch it again, and yes you will get much higher frames with a OC I7 vs a stock.. probably in the neighborhood of 15-25 % higher FPS and also GHz does not = GHz.. when it comes to performance on different brand chips in other words and I7 at 3 ghz.. is about 1.5x faster than last gen intel or current gen amd.. so you can do math 6 core amd is about same speed as I7 4 core GHZ for GHZ so yes 6 core low end amd is very good choice even cheaper than I7 and aaaaalmost as fast if you OC, if your not OC skip it (6 core amd)

as for OC the GPU also must do lol, so easy to do also, just get into CCC in ati cards.. and click the button to release slide and add 100mhz to the GPU speed.. done) that will help alot so easy to do, and 5850 will OC like a beast recommended highly amd cards run nice and cool, if u decide to OC the GPU make sure it either A exhausts out the case.. or B you have at least 2 large or three small fans blowing inside the case