For the Athlon 64 3500+, you are getting the Venice core right? It adds SSE3 support, works better with mismatched memory, and overclocking appears very promising.
With better cooling, 2.8GHz should be easy to reach. If you are serious and throw some higher powered cooling at it, 3GHz is a definite possibility. So this CPU is a good buy for the power you get.
*Fact: Microsoft Window's Blue Screen of Death vs Computerforums.org's White Screen of Death. Which is worse?