Is this a cooler you already own? Or planning to buy?
It'll probably depend a lot on what you mean by overclocking... if you plan to get every last ounce of performance out of the E6320, that usually means adding a bunch of voltage to the cpu = lots of heat and in that case, I'd say likely no.
If you just plan to do mild / moderate overclocking - whatever you can get without adding any (or not more than a bump or two) of voltage, then I'd say maybe.
There are a good selection of "bang for buck" coolers that do fit in that second category, priced in the $20 - $36 range, but you haven't listed your requirements (don't know if height is a concern, or weight, or noise, or cost, etc), so it's hard to answer.
The design of that cooler looks like it should work for mild/moderate overclockng (heck, the stock Intel heatsink does), but there are some coolers that end up performing worse than the stock HSF, so without seeing any reviews, I can't say for sure.
After a little more looking around, I did see several reviews of the earlier "Silent 775" model, which is just marginally better than the stock HSF. The one you listed above looks like an upgrade to the Silent 775 (two more heatpipes, etc), so all other things being equal, it should at lest handle mild-to-moderate overclocking.
Just keep in mind:
- increasing the FSB to get faster cpu speed = fairly linear increase in heat.
- increasing the voltage to the cpu = squared increase in heat
...once you start increasing the voltage, the heat generated goes up much faster. So I'd start by seeing how high you can get it without adjusting the voltage first and keep an eye on load temps if/when you have to add voltage to go higher.