How do you back up a dell inspiron laptop harddrive?

My wife's Dell laptop started having problems. So I removed the hard drive and purchase a SATA kit to connect it to my laptop to back up her important files before doing a full system restore. I have it all hooked up but when I goto the drive on My Computer it tells me that Access Denied. How do I get access to the drive and get my files?How do you back up a dell inspiron laptop harddrive?Why not put it back and back up to CD or DVDs?