I just had a very similar sounding problem recently. It turned out to be a wheel bearing. Jack the car up and see if you can wiggle the wheel from top to bottom...if so, it's definitley a bad bearing.

1999 Silver Frost SVT #609 of 2760 Quaife, lightened SVT Flywheel, SPEC stage II clutch, removed resonator, k&n drop in - various other goodies too.