I don't have any experience with using my cell phone as my modem but I have heard some good things about sprint's wireless network. This article states that they range from 50-70 kbps with bursts up to 144 kbps. Definitely faster than dial-up.

I think Derrick uses it (though I'm not positive) so maybe he can have some input.
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Russ
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"The difference between a successful person and others is not a lack of strength, not a lack of knowledge, but rather a lack of will." Vince Lombardi