Let the hive mind of Engadget get that for you.
"As someone who doesn't reside in the USA, I was wondering what would be the best way to get internet for my computer in the US for a couple of weeks? If it were Europe I know I'd look for some prepaid data. Is there anything similar offered by American carriers? A MiFi or a data SIM that I can tether from would work, but I'm trying to maintain a tight budget. Help!"
I think your MacBook pro Update is incorrect. Please see link below that states (Under Third Party:) that the Update 10.4.7 fixes the driver issue for Powerbook, not MacBook (Pro). I ordered one so I'll post a message letting you know my findings.
Quote:
"Adds support for Sierra wireless cards AirCard 580 (AC580), PC5220, and for the Novatel V620, S620, and U730 wireless cards for PowerBook computers."
http://docs.info.apple.com/article.html?artnum=303771
The fact that Express Card/34 is taking so long to support is really irritating.