Hi Lee and Linda,
Check out the
3gstore.com and give them a call to discuss.
I have an internal antenna, and an external antenna, and the Wilson Signal Booster. My experience is that most of the improvement I get is from the signal booster. The external antenna adds does better than the internal.
If you use 192.168.1.1 as the internet address in your browser, it'll let you log into the Mifi (assuming you remember the password and are connected to the Mifi). Under one of the menus (advanced maybe), you'll find diagnostics and modem diagnostics. Scroll through that screen and look for EVDO (3G signal strength). You can refresh that screen to see how much improvement you get. Best I remember, you need a signal level of -88 to get a reasonable connection. -80 is very good. If you're having trouble, you'll see it on this screen.