In my new job, I was provided with a VMWare image running Ubuntu 7.10 which contains my own dev environment. I wanted to run it using VirtualBox instead of VMWare. The migration was fairly straight-forward since VirtualBox can read VMWare disk files. However, networking didn't work.
I found the answer here: http://mydebian.blogdns.org/?p=177#comments
Basically, it was due to persistent udev rules. To fix it, I did this: