1. M2N68-AM Plus does NOT support PII-955/965 according to the CPU support list of this MB. Hence, PII-945 rev C3
is the best choice if you don't want to buy a new MB.http://www.asus.com/product.aspx?P_ID=N9gfnjYUinlROPLf
2. 965 is potentially a factory overclocked 955 and so the extra $40 is definitely a waste!