I always used my Verizon Air card. I had very good service and rarely in a spot where it did not work. If I had a cell signal I had internet. This way your not restricted to using only at the T/S but at the long waits at the receivers or rest areas.

Here are some examples from Verizon.

The speed of the Verizon Wireless data network is measured in Kilobits (kb) per second. However, the amount of data transmitted over the Verizon Wireless data network is measured in Kilobytes (KB), Megabytes (MB) or Gigabytes (GB).
Bit - A unit of information that respresent a single character.
Byte - A unit of information composed of 8 bits.
Kilobyte - 1024 bytes (measuring the number of kilobytes tells you the size of a file and/or the amount of data you have used).
Megabyte - 1024 Kilobytes (measuring the number of megabytes tells you the size of a file and/or the amount of data you have used).
Gigabyte - 1024 Megabytes (measuring the number of gigabytes tells you the amount of data you have used).



Examples

E-mail (1 text page without attachments) 3 KB
(Based on this assumption, you would need to send and/or receive approximately 1,747,627 e-mails in a month to reach 5 GB)

Word Document (5 text pages) 70 KB
(Based on this assumption, you would need to download approximately 74,897 Word Documents in a month to reach 5 GB)

Typical Web Page lookup 150 KB
(Based on this assumption, you would need to look up approximately 34,952 web pages in a month (or over one thousand per day) to reach 5 GB)

Low Resolution Digital Photo 500 KB
(Based on this assumption, you would need to download approximately 10,485 low resolution digital photos in a month to reach 5 GB)

PowerPoint Presentation (20 pages text & light graphics) 3 MB
(Based on this assumption, you would need to download approximately 1,707 PowerPoint presentations in a month to reach 5 GB)

V CAST Music Over-the-Air Download (3-minute song) 2 MB
(Based on this assumption, you would need to download approximately 2,560 songs in a month to reach 5 GB)

V CAST Music PC Download (3-minute song) 4 MB
(Based on this assumption, you would need to download approximately 1,280 songs in a month (or over 40 per day) to reach 5 GB)

Note: The above examples are just estimates, based on approximate size assumptions. Actual file sizes and user experiences will vary.

I guess I'll stay happy with my slower aircard...my contract specifies "unlimited usage and no roaming charges" anywhere in the US!! 8)

You can also get a USB aircard that'll work on any computer (mac or pc). I'll be upgrading my PCMIA aircard to a USB one at the first of the month. It's hard to believe I've had it for 2 years now.

The new ones (USB for sure) also have GPS built in. I just wonder if I can use that GPS in place of my current USB GPS receiver.