Hi Ryan:
Thanks for the link. I read the following:
"USB is far from the ideal medium for network access, if you can get your hands on an ethernet modem you may save yourself some trouble. If you have a modem that can connect both via USB and ethernet you should use the ethernet connection."
In view of the above, I have decided not to use Ubuntu and go back to my Windows XP. It seems to me that Linux is still a software for people who have certain computer skills. For mainstream users Windows or Mac OX X is a much better alternative.
Once again, thanks for your assistance.
Omar.-