Each Dell owner has the opportunity to register with Dell Support.
I have several Dell computers, all listed to my support username login at Dell.
The particular machine is then identified to Dell via its Service Tag Number which is a seven digit randomly generated code label that is assigned to the machine at time of manufacture.
The Service Tag is printed on an ID sticker on the outside of the tower case.
In the event that you do not find such a tag, you can use Everest 2.20, which you can download free, here:
http://www.majorgeeks.com/download4181.html
The Dell owner account was most likely created and confirmed back to a valid email account the owner had at the time of purchase or registration with Dell Support.
The Dell owner support account "can" be changed to a current email address account if the owner has changed email features. It may be possible to change the account to an active email address if the owner remembers the login email account address, the username and the password.
If the owner doesn't remember that information, it may still be possible to access Dell Support via phone email or phone contact to change the user support access login information.
With the Service Tag number, Dell Support will navigate you to a page with all the drivers for that type of machine with those features. Your specific machine may not have or need all the devices listed on the page you receive from Dell Support, but you should be able to figure out what you need from a combination of using your machines Device Manager, System Information Tool, and Everest 2.20.
Edit: By the way, after installing the Windows operating system, the first drivers you should install would be the motherboard Chipset Drivers.
Then device drivers after that.
Best Regards