What's the difference between retail and system builders copy?

Question

If I buy system builders copy of windows vista to put on a comp that i'm selling to somebody..what is the difference between this and the retail version? Can i use the retail verson on more than one computer? Or can i uset hte system builders copy for multiple? Is it illegal to use the retail on computers you are going to sell?

Answer 1

Retail you can use over and over again and OEM you can only use once I think.