You'll have to link me to fan choices (don't have too much time to surf at work).

Also, I don't know anything about Sempron processors... If you were asking if a 2.4ghz Pentium 4 was better than a 2.0ghz Athlon 64, then I would say definately not--not by a long shot. However, I can't guarantee the same for a Sempron. I think you should shop around for a cheaper Athlon 64-bit processor and mobo. Pricewatch has Athlon 64-bitters around $150, so I know you can get something cheaper than that website you're linking.

What is it they say about silence being golden?