Question About DELL N5010 Laptop!

Ok so i have a DELL n5010 Laptop its come with Windows 7 Home Premium OA .. ( Genuine ) but its 4 years OLD window now..


So my Question is can i install New Windows 7 Home Premium from a Local Windows DVD .. and use the SAME Product key to activate the windows ? or this product key is only for one time use ? i really need to install new windows my current windows is working SO damn SLOW ...


Please Help

thanks in advance.