PDA plans for cellphone

[ddubois]

I'm thinking about upgrading my generic piece o' crap candy bar cell phone into a AT&T Tilt smartphone, but it looks like I'd be required to get a PDA plan for the mail in rebate to qualify. I'm not sure exactly what that includes. I don't need/want to get another email address, or even get my email through my phone at all, but I do want to be able to occasionally look things up on the web, get directions from google maps (Tilt has a GPS), download 3rd party games/apps, etc.

The two most obvious plan choices are "PDA Personal 20 MB" and "PDA Personal Max with 1500 Messages", but what perplexes me is how could I possibly be expected to make a two-year commitment to a threshold of data usage when I have no idea what 20MB really means? I mean, it's not like minutes, where a normal human can figure out how much of a talker they are; they're expecting me to not only gauge how much I'll be browsing, but what the sizes of the web pages I'd be downloading would total up to in kilobytes?! Anyone with empirical experience know if 20MB is enough?

Right now we pay $50 a month for "FamilyTalk Nation 500 Rollover & 5000 Night/Weekend Minutes" for our two cell phones, and I don't like the idea of all of a sudden paying $95 a month just so I can google something once a week.