If you plan to overclock get FX 8120..It's the same CPU with FX 8150.
I would also get a cheaper 990FX motherboard like Gigabyte GA-990FXA-UD3
Regarding the CPU...
This is pretty much the same case as with the PII 955 v. PII 970, right? It's safe to say that generally the 8150 will overclock higher than the 8120, just like with the Phenoms, because better quiality chips are chosen for the top models (8150 and 970, respectively) since they have to pass thermal tests etc. Correct me if i'm wrong, though.
I chose the Sabertooth because, as you mentioned, I plan to OC as high as I can on air and the Sabertooth seems to be creaeted just for that, according to the generally positive reviews, especially in OC, and the stable power and temperature management.
I'll definitely look into the Gigabyte GA-990FXA-UD3, though - thanks for the advice!
Why would you go with AMD while Intel is just the leader on the market right now?
Well, according to tests, the 8150 is the best CPU (for a reasonable price) on the market for the tasks which I will perform. Plus, I've allways used AMD CPU's so far and have had only good experiences, thus see no reason to switch to Intel, though I'm sure they have excellent products as well.
I don't like AMD or Intel, I like good CPU's - the 8150 seems to be one. I'm aware its single-threaded performance is quite lower than that of the Intel counterparts, but there aren't many single-threaded applications left on the maret and multi-threading will only become more popular.