The Intel D975XBXLKR doesn't support SATA 2.
While its true that there are no guarantees at this point that any MB on the market will be compatible with Conroe (including the current Intel boards), its also quite possible that 945 and up will be compatible. Bottom line, if you care more about being Conroe compatible than having a system now, wait to be sure. Nvidia is about to release (NF5?) their version of the Conroe supporting chipset. However I'm betting any 975x will work as well. More about the voltage regulator theory here, but its all speculation at this point:
http://www.xbitlabs.com/news/cpu/display/20060202133551.html
NF5:
http://www.bjorn3d.com/read.php?cID=922
If you read the TG review, they already calculated that PSUs run @ 80% efficiency and recommended at least a 500w to overcome that. Probably a little overkill for most situations, but better safe than sorry. It really does no good to use a bigger PSU than you need as running at 40% capacity vs running at 80% capacity makes little difference to a good PSU. Trick is to stick to a name brand that puts out true power. Most generic PSUs don't actually put out what they claim (usually 75-85% of their claim). Last thing to skimp on is the PSU as it can take other hardware out when it goes. Since the 805 @ 4.3GHz only uses around 230w, any good 500w should be more than enough unless you're also running SLI with 2x7900GTX or 2x1900XTX, and even then it might work fine. The 805 @ 4.3GHz draws about the same as the P-E 965. Nothing wrong with going to a 550w or 600w, but not necessary either.
Antec makes great PSUs. I'll vouch for TruePower and SmartPower series, never tried the other new series. The best bang for the buck on the market IMO. If you want to spend more, I've been pretty happy with OCZ (Topower) PowerStream (600w) as well. I'd avoid Thermaltake and Tagan (had issues with both) and any generic brands.
One other bit of advice, if I were spending the money for a 7900GT or GTX at this point and using air cooling on the GPU, I wouldn't go with anything but BFG for the lifetime warranty (does any other vid card offer that?). Reason being that 68**, 78**, and 79** series all have pretty high failure rates, for every manufacturer. If you plan on keeping your card for a few years, or getting something for it if/when you sell it, the lifetime warranty is definitely worth the extra expense IMO. Nothing worse than having your warranty run out just before you expensive vid card dies. Keep in mind that you void the warranty of any card when you put water cooling on it.
🙂