Tim is right, READ, RED, READ. The same basic overclocking techniques that apply to the current chips also will apply to the older ones. One big advantage you will have is that there are a lot of better heat sinks out there now than were available in that chips heyday, an HSF from a socket "A" will fit right on it.
Although the K6-2 is not known to be a great overclocker, the motherboard you have is one of the best from that era. I've built several on that board with very good results. I prefer the K6III chips and they seem to overclock respectfully. As a matter of fact I'm on a K6III+ 450 @ 616MHz as I write this, that's 37% over default. I opened this machine up tonight to repair a stuck CD ROM. While I was in there I figured, why not? Previously I had this running at 600MHz (6*100). Changed the FSB to 112MHz, lowered the multiplier to 5.5 and upped the core voltage to 2.4 and installed an old Global Win FOP32 that I had laying around.
I should mention that this is a "+" series chip, originally intended for the mobile market. If you would happen to get one of these, you "MUST" upgrade the BIOS to "JE4330" . The upgrade is located on FIC's website. Although FIC never "officially" supported this chip for their desktop motherboards, they did release this BIOS upgrade in a beta version.
If you already have this CPU / motherboard combination, go ahead and see what you can get out of it. But I would be a little reluctant to invest too much money into it though. With the cost of the DURONS dropping almost daily and the first generation motherboards available now for less than $80.00 with onboard sound it makes more sense to do the CPU / motherboard combination upgrade, leaving you with a viable upgrade path for the future.
Good Luck!
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