Since the installation did not complete, the Ubuntu partition may be non-bootable. To verify, boot the Ubuntu cd. You should have a menu of options (Install, boot from hard drive, etc.). Select boot from hard drive. If the Ubuntu installation is bootable, it will boot successfully. If it isn't bootable, you should get some kind of error message telling you so.
The installation probably stopped at the "waiting for network connection" phase because a network connection would be necessary after installation to update all installed packages to the latest version.
To delete the Ubuntu partition, you have two options:
1) boot windows and use windows software to reclaim the Ubuntu partition for windows.
2) boot the Ubuntu cd as a live cd. Run gparted (or other partition management app of your choice) to remove the Ubuntu partition, and extend the windows partition to take up the free space. Complete the task and write a new partition table.