internet connectivity

This is obviously a problem related to the OS / hardware compatibility. To troubleshoot the problem, the best is
1) to identify which network chipset/cards you have in your computer
2) then look in Ubuntu community forums ( ubuntuforums.org/ ) if you find a similar "problem"
3) if not, ask your question there.

First step
how to identify your hardware:
From manufacturer datasheets or you can use the command "lshw" in a terminal to list the hardware components of your computer. If you use an internal wifi/ethernet card, it should appear as a pci device.

Some more information on Supported Wifi cards in Ubuntu:
help.ubuntu.com/community/WifiDocs/WirelessCardsSupported
Ubuntu documentation related to network:
help.ubuntu.com/search.html?cof=FORID%3A...etwork&sa=Search