hyperthreading does practically nothing for gaming, and when surfing you probably wouldnt notice if your 3ghz cpu was running at half speed. hyperthreading, and especially CPU with dual cores, seems likely to become more prominent in the medium-long term future, but games will make decent use of 64bit before HT becomes a serious benefit for gaming.
TBH, neither tech is anything like essential right now, and wont suddenly be needed for direct-x 9.1 or something. Just go look at a few CPU comparison "benchmark" roundups and get which ever one is faster -- that is faster on software that is relevant to you (i.e. focus on game benchmarks) -- for whatever money you have. btw remember to not look only at CPU price but the overall effect, i.e. include suitable motherboard.