[Baron Munchausen]

From all I have heard to date the software has to support either HT or multiple cores. As others have noted, most games do not currently support either. But if your OS at least supports these, you will probably see at least some benefit as the other things your computer is doing while you are gaming will interfere less with the game performance. Unless you are doing something fairly processor intensive in the background when gaming I suspect that the HT CPU at the higher clock rate will give you better performance with current generation games, though.

Perhaps you should consider other factors. What is the total power draw of these various processors? How hard are they to cool? (Surface area to power ratio, etc.) Since the performance difference will probably be marginal the one that runs cooler might be the smarter investment since you expect to run your system at full throttle for extended periods.