|Make sure you install all device drivers appropriate for your computer. It doesn't sound like you installed any drivers after reinstalling your operating system. Make sure you get your motherboard chipset, video card, and any other device drivers not yet installed. Open up Device Manager (Start > Run > type: devmgmt.msc) and look for devices with yellow icons.|
Keep in mind, not all listed drivers on Dell's website will apply to your computer. Ask if you have specific questions.
Apologies if I don't respond to your reply immediately. I don't check this site daily, but you're welcome to PM me as a reminder.