For $140 total you can get the new nforce2 ultra 400 motherboard plus a cpu that overclocks higher than the 3200+ is at stock speed.
http://www.newegg.com/app/viewproduct.asp?description=13-138-227&refer=pricewatch
http://www.svc.com/lqtamdxp17tb.html
Any amd cpu can be set to run at any fsb the motherboard can handle as long as the motherboard allows multiplier adjusting.
The faster the cpu the more vital memory speed becomes. "big advantage" is probably too strong a term though. If you were to ask is pc2700 worth the extra bucks over pc2100 the answer imo is yes, but if you already had the pc2100 there is not enough advantage to justify chucking the pc2100 and buying new faster memory.
There has been more talk of late about buying higher quality memory since it is true that cheap/generic is unreliable in a dual channel system, but since amd cpus do not really benefit from dual channel I don't know why you wouldn't buy a low priced $65 512mb stick of pc3500 and hope it runs at 433mhz like its supposed to or at least comes close to it, then set your fsb to match it.
If I had to make a bet as to what is the best odds bang for the buck system right now it would be the biostar nforce2 ultra 400 board above for $83 (it was only $80 a couple days ago), the svc.com $60 1700+ that oc's to 2.4g or higher, a 512mb stick of pc3500 for $65-$70 from whoever, then experiment to find the max fsb and memory speed that match, figuring it will be between 200 and 230, then run the system at 11x220 or whatever. That's $200 for mobo, cpu, memory.