Inspiron 1501 with Verizon Cell Modem Dropout Problems

I have an Inspiron 1501 that connects very well with the internal 1390 WLAN Mini-Card, but when using a USB720 Verizon cell modem and Verizon service, I keep getting dropouts from the internet connection.  When it connects, it is always quite slow, and eventually drops out after several minutes.  I have to continually re-connect to get back onto the internet.  The slowness may be due to my service contract (I don't know the speed, etc., probably the cheapest package).

 

Is anyone having similar problems with their Vista machine?  Any ideas are appreciated.

 

Also, in case it matters, I see that my driver for the 1390 is dated 11/13/2006 and version 4.102.15.56.  On the Dell website, at http://support.us.dell.com/support/downloads/download.aspx?c=us&cs=19&l=en&s=dhs&releaseid=R151519&formatcnt=1&libid=0&fileid=202138,  I see that the latest driver is dated 3/22/2007 and is recommended.  However, when Windows is asked to check for driver updates, it tells me that I have the correct driver installed.  Could this possibly be a problem with the USB Cell modem?  Thanks SO MUCH for any help.

 

-Rockspecialist