I have used one of the AT&T aircards and had both good and bad experiences. I agree with others on here, it depends on your cell reception. My best experiences have been with strong cell reception, my worst experiences when my cell reception was so low that I could barely make a call. At that point, 56k Modem dial up is faster!!
The G3 network from AT&T is supposed to be much faster, but I have no idea how far the coverage area goes, and also if they sell a G3 aircard?
Sorry, not sure if this information helps you or not Shirley. I guess my best recommendation would be to make some kind of deal to try the set up for a few days, and be able to get your money back (easily!) if it wasn't all it was cracked up to be.
Hope that helps,
Kandy