Scott, the iPad is NOT a computer. You can't type a word document on it, you can't plug your usb thumb drive into it, you can't hoom it to you car and tune with it. But you CAN load it up with videos, you can surf the internet (the real internet, minus flash video), you can connect it to a stereo and play your music,you can use it to read e-books, and you can download tons of apps. If you want a portable COMPUTER, this is not for you. If you to read e-books, check your email, watch videos, surf the internet then this is for you.
And the wifi version can be connected to any wifi source, be it the wireless router in your house, the wireless at McDonalds, the wireless at the airport, or the Verizon/ATT/Sprint wifi hotspot you may have. The 3G radio equipped version will only work with AT&T.
Also, there are a bunch of cheap android based tablets on the horizon. I'd look into one of those.