You can PM me with your info, and I'll tell you if you ahve the $250.00 deposit. Whe was the last time you had your credit ran by Sprint?
Have you checked Sprint's great plans for SERO on www.sprint.com/sero?
I'm pretty sure Sprint would be your deciding factor.
Even with a SERO Blackberry data plan, that is unmilited (no cap like other carriers), EvDO speeds, and allowed to tether (phone as a modem).
If you don't mind me asking, why did you make the choices (carriers)?
I'm trying to help you make your best choice, even thogh I work for Sprint, I'm not biased...not too mush...lol).
I honestly try to help EVERYONE who asks for my assistance.

Cheers,
-Yean