If they're halfway decent fixed gear wheels, they probably won't be compatible with a geared drivetrain. The crank you may be able to use, if its a road double converted to a single ring for fixed gear use. I'm sure you can get the rings you need from a bf member. Its nice to have bars, stem, seatpost, brakes and saddle. If the wheels are any good you can sell them and get your extra $100 back, and still have all that extra equipment I just mentioned. Then you'd just need derailleurs, shifters, and the right wheelset.