You're trying to find drivers for an almost 10 year old machine that didn't ship with anything beyond Windows XP. It's no wonder Dell doesn't provide Windows 7 drivers. There <may> be some generic drivers available from the various hardware manufacturers (such as Intel) but don't hold your breath.
Try Iobit Driver Booster. The free version will find the drivers you need. (When you install it you might want to uncheck the box that offers to install Advanced SystemCare Ultimate BTW) Hope that helps. And to avoid all the nag screens that will surely plague you uninstall the software after you're done updating the drivers.