I am considering building a cheap 500 dollar PC almost identical to the current SBM budget build, albeit an Athlon X4. Is it worth waiting for the new Sandybridge processors? I.E: will I be able to use a sandy bridge or will the price just of the cheap Athlon drop a buck or two?
 The real question is, at the price range of 500 bucks, will a sandy bridge PLATFORM be a possible 500 dollar build for games?
I don't think a Sandy Bridge build will be quite feasible for what you could do with a current AMD set up. Intel tends to be much more expensive (for a good reason, of course) and the new stuff also tends to be a bit pricier.
I would expect the cheapest H67 boards to be about $20-30 more than the cheap H55 boards (in other words, ~$90). However, only the i5 and i7 SB CPUs are launching in January, and the cheapest of that lot costs Newegg $177, in lots of 1000.
The dual cores hit Feb 20th, and the Pentiums in Q2 (except one, but that's clocked at an anemic 2 GHz).
As for buying a cheap one and OCing the hell out of it, you'd have to wait until reviews came out, but FSB OC is dead with SB.
Don't go with SB at such a low price range, your not going to get the best bang for your buck. Batuchka's build is a beauty at 500$. Basically 500$ at least. SB is not going to be cheap, I defiantly think the minimum budget would be at least 800$ to do an SB build. Also just to put that in there. SB's lower end is coming out in January. Not the i7 SB's. Those come out in Q2 Q3 of 2011. Not Q1. Or at least so I hear.
Well the current set up I have in mind is about 450.
18 dollars for Samsung DVD
25 dollars for Rosewill Case from previous 400 dollar SBM
Skimping on the power supply and getting the Cooler Master ELITE 460 power supply from the 400 dollar SBM for 30 dollars.
WD Blue 500 GB hard drive for 50 dollars.
Gigabyte GA-770t-usb3 for 70 dollars - 10 rebate
Same ASUS gtx460 768 for 140 dollars - 20 dollars rebate
DDR3 1600 2x2GB corsair 1.65 v for 50 - 10 rebate
And the Athlon 640 for 100 bucks
for a totale of 480 - 40 rebates + 7 shipping.