Can't access folder on hard drive

Hello,

I recently installed a new hard drive on my computer and installed the operating system (XP Pro) on it. I in turn took the old hard drive and slaved it. However, now that I've slaved this drive, when I try to open the folder that contains about 130gigs worth of info, I get an "access denied" message. If I mouse over the folder, it show's it to be empty. What do I need to do in order to access this folder?