|Sounds to me like he gave a valid reason for getting Vista off a "7 yr old Dell lat d-800...".|
It's an old Dell not suitable to run Vista; 2000 or XP would be appropriate though.
You can use DBAN to wipe the hdd and then install 2000Pro...
How to use DBAN here...
Can I assume you have the reinstall/recovery disk that came with your Dell? If not, go to Dell Support site and the "Service Tag Number" on the laptop will lead you to the drivers you need to get everything working again.
Post back if you need more help.