I installed VMware on Windows 7 and got Ubuntu 3.5.0-23-generic (64-bit) running. Brought up Firefox, but was unable to get to the internet. In xterm, tried to ping 192.168.1.1 (my router) with no luck. (I can do that in my Windows and Cygwin consoles.)
Looking around EE for clues and I found some information that may be helpful.
I have Norton 360 installed.
VM setting for Ubuntu Network Adapter was set to NAT. I changed it to Bridged (not sure of what this does).
In xterm, I ran:
sudo iptables -F
sudo iptables -L
I rebooted my router since another person's problem was solved that way - something about DHCP. Not sure why rebooting router fixed the Ubuntu DHCP problem.