Perhaps this article: http://support.microsoft.com/kb/314082
can help you.
About those two partitions you're seeing, the 39mb is something Dell puts on all of their compuetrs. I'm not really sure what it does, but I think it has something to do with the boot process.
The partition of 4.63gb is either:
1. If the Windows folder isn't installed onto the viewable partition, it may installed onto there.
2. It's probably a recovery partition to restore the computer back to factory settings.
If it is number 2, you may be able to reinstall Windows from it, but it will probably have all the junk on it that came preinstalled on the computer. If you did want to try this method, you can access it at the Dell bootup screen (where you would press F# or delete to enter the BIOS) in which it may be an option. It may also be an actual option in the BIOS.
"I think there is a world market for maybe five computers." - Thomas Watson, Chairman of IBM, 1943