You should find CLR-calcium, lime, and rust remover at wal-mart or k-mart. Maaaaybee in an auto parts store, but I would check in the household cleaning products section of wal-mart or K-mart. CLR isn't too hard to find.
Not trying to knock the original poster, I've never tried this so it may be the miracle fix, but I'm just a little wary of trying stuff like this. But I am anal about my cars. If this works good with no negative side effects then I'd have to say:goodjob: Good Job Sir.