If I had Vista, I would be ready for the funny farm too.
There are two tricks that can be helpful in uninstalling a program or driver from Vista:
A. push control alt delete and start the task manager. Click the processes tab. Find the Dell processes that are running, on the list. Now highlight the dell processes, and click "end process or stop process." Now check the rest of the list and END all the Dell processes.
Now that the processes have been ended, go into the control panel and delete the software or drivers. Bingo.
B. Start the computer in safe mode. When you do this, the printer software and drivers will not be running. Go into the control panel and delete the dell printer software.
Note: Look for a flashing icon in your taskbar. If you see that, click on the icon, and then click "allow." Vista is blocking your task, and asking you for permission to carry out the task.
Note: To install new drivers or software, it is necessary to shut off the antivirus FIRST.