From what I see in your signature, you already have a very good CPU, why would you change it?
I would definitly get the 3200+ @ 90nm, why pay more if you can run both the 3200+ and 3500+ at nearly the same speed when overclocked.
There is 2 reason to overclock...
1. Get the most performance from cheap hardware
2. Get the most of high-end hardware
So, obviously, the best overclocker's choice for AMD64 socket 939 is the 3000+ @ 90nm or the FX-55. All AMD 90nm chips can easily reach 2.4GHz, so why getting the fastest 90nm chips when the slowest can make it!
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A7N8X / <font color=green><b>AMD Sempron 2800+</b></font color=green> <-- <i>Is this affecting my credibility???</i>
Kingston DDR333 2x256Megs
<font color=red>Radeon 8500 128Megs</font color=red> @ C:275/M:290