be very, very careful.
data charges can amass very quickly just performing normal web browsing.
i know that here in canada, rogers data prices are exorbanant. i'd recommend phoning cingular, or your provider, and finding out what your plan charges you for data/kb or mb.
i've read posts on cellular forums (howardforums.com primarily) of people getting bills in the upwards of $100,000 of data.