There could be a lot of rasons for this. Are you too far form the closest WAP that will cause a slower speed. Is there a lot of RF interfierence in your area (are you near power lines, do you have a lot of cordless phones/other electronics running, is there a ham radio operator or another type of radio transmiter near you ?). RF will cause a weaker/slower signial also. Finaly check the manual that came with your WAP it may be force set slow, there should be a way to adjust that.
Are the other computers on your network pulling down faster downlads? this may just be a cable problem 60 isn't bad for cable if there a lot of people on your segment.