Just got one for Christmas!! I mean a IrDA converter. I got a Nokia 6100 myself, but technically they're the same. The IR port of the 6610 is located on top of the phone, next to the power button.
USB to IrDA are not that expensive, and the functionality is pretty high. You can backup the addresses and schedules of your phone. You can send MIDI files to your phone and use them as ringtones, and pictures to use as backgrounds. And of course games! You CAN'T store the ringtones from your phone to your pc. Well atleast not with the official software.
My advise: buy an IrDA converter!!! You won't regret it.