Lets try and make things a little clearer for you: you have various devices in your laptop: graphics cards, sound cards, dvd drives etc. Some of them are immediately recognised (or perhaps after a little coaxing from a config utility) by Windows so it knows what they are, what drivers they need and can keep tabs on whether they are up to date. Your problem is that Windows doesn't know what your "DVD" drive is so it doesn't know how to set it up or how to install a driver. As a result it doesn't maintain it on it's driver list.
You need to identify what dvd drive it is, go to the Dell website and download the Vista driver for it. You then go into Start/control panel/device manager and you will probably see an item listed that has a yellow question mark next to it and called something like "unrecognised device". If you rt click this device and select update driver. Select the option to locate the driver yourself. Click on browse and go to the folder where you saved the downloaded driver. Highlight it and click ok. Should tell you driver installed and device is working correctly. Windows now knows what it is. Close all windows and see if the dvd drive appears in Explorer.
Unfortunately, computers are logical and thus very precise and use a very precise jargon. My peers may appear to be pedantic but that is only because they are using the language of computing and this can sometimes appear confusing.