Dear Rob,

First things first : You should have kept the CD / DVD's that came along with the computer, in a safe place, for future use.

Incase you did have them, then using that "R" option (Recovery Option), through the disc, you could have easily repaired the operating system in your computer.

That is your first mistake : not keeping the discs safely.

Second mistake : Why did you get the operating system loaded into your computer by a "friend". Trust me, if he is your friend, then he would NEVER load a pirated version of the operating system into your computer. 

Pirated version, hence the message that you need to buy genuine windows. 

Third observation, you have to know what was the operating system on your computer ? windows XP, vista ? which edition ?

OK, to get an operating system disc from Dell : you can get it for a lesser price from Dell, if you have a valid Hardware Warranty on the computer, if not, you will have to buy a fresh / new retail version of it : you can get that also through Dell, ofcourse that would be at current market price.

You can email me, if you wish and I shall be glad to guide you  

<ADMIN NOTE : Email id removed per privacy policy>

Dell will send one free replacement of your original set of disks if you fill out the form here. You must be in the US and be the original owner. And you cannot "save to a diff memory" whatever that means. You will have to reformat the disk and install windows when you get the disk. Do not let that 'friend' do it.