|I will post here what I normally tell people...|
It takes time to get systems completely setup. Installing is just part of it. You still need to run Updates, setup personal information such as name and initials and other things like Flash Player Plug-ins for your Internet Browser and so on.
I never recommend any one clean their system and reinstall from scratch because more often than not, it leaves them unsatisfied because they find that they did not have all of the programs they once had.
That being said, you need a Windows Systems disk. Boot from it in the Recovery Console and run the command Format C: to wipe the drive. Then reboot and run the Windows Setup as normal.
Also, you will want to make a log of what is installed on your system so that you can track down installs for the applications you wish to readd once you are done. The simplest way to do this is to go to the Control Panel and Run the Add and Remove Programs which will give you a list of installed applications.
Last you will need to track down all of the drivers for your computer. Go to Dells web site and do a search for your model number. Then download and burn all of the drivers to a CD. You will need to reinstall them if the systems disk from Dell does not already have them.
Again, I stress this is not the best pan. You would be better off going to your Add Remove Programs and start removing what you don't want.