My current plan with Cingular/ATT will expire in a couple of months but I can upgrade sooner. If I get the right phone will the cheapest $19.99 media plan from ATT be sufficient to access the Internet and, most importantly, use Skype on my N800?

I saw that T-Mobile has the $29.99 Internet option (including Hot Spot access). Is that any better than what ATT has to offer? Any specific phone recommendations in addition to the ones mentioned above? Thanks for your help.