Don't get a single core 3800+, that's for sure. It's a small cache 12x multiplier CPU. Instead, get the cheaper 3700+ with larger cache and 11x multi.
BTW, the fact that "dual core overclocks very easily" is not an argument speaking for dual core. 0.09 single cores like the 3700+ San Diego overclock great as well. For this particular CPU, just set FSB to 240, RAM divider to 166 and HTT to x4. Voila, you have a 2.64 GHz processor that will perform on par with the overpriced FX-60 in most games, for a fraction of its price. Just without the second core, that usually doesn't matter anyway.
If you're into heavy multitasking (encoding, etc.), give dual a shot. Otherwise, for gaming and typical desktop activities, I'd actually recommend the a/m single core 3700+. It's cheaper, overclocks like a devil, and is often faster in games than even an equally clocked dual core CPU. Plus, it doesn't have any dual core typical issues. Despite hotfixes and drivers, it seems like not all dual core bugs have been fixed yet. I personally will wait a bit and get dual core once it's really bug-free and actually yields some real performance benefits in games.