|Sounds like he has a pretty bad virus infection. Can you boot to Safe Mode? Can you run any programs at all? If so, try a System Restore.|
You really should have an OS CD. If there's no data on there that he needs, there is a Dell Recovery Partition on the drive. Assuming of course, that nobody wiped it out.
Press F12 when you boot the computer to bring up the boot options menu. The one you want is either the first or second in the bottom set of options.
"So won’t you give this man his wings
What a shame
To have to beg you to see
We’re not all the same
What a shame" - Shinedown