Won't matter unless the 750 also can do 1.7ghz and 2.1ghz in HSDPA since
those are the two frequencies that T-Mo will be using for HSDPA as a result
of them winning the FCC auction for those two spectrums in the US. I know
of no devices in existence that will also do 1.7ghz in addition to the
850mhz, 1.9ghz and 2.1ghz that many current devices will do. You'll likely
not see T-mobile US capable devices until this Summer.

Dave