Probably hundreds
I work in a computer superstore (UK's PC World) and am the stores 'Apple Guy' so i do all the selling for everything Apple.
Outside of work though i've convinced only 2 people that i know of, My Ex used a toshiba laptop until i bought my new MBP and handed her down my old 12" iBook G4, and my younger brother has just gone out and bought a new iMac.
A few people from previous employments have also switched to Macs, but although i did talk to them alot about them, they switched after i left so can't really take credit for them.