Hey Kadne!
Windows has a security feature called User Account Control (UAC). Even if you are an administrator, UAC runs most applications with standard user permissions to prevent unauthorized changes to the system. When an application needs to make a change to a protected system folder (like Program Files or C:), UAC will prompt you for approval.
Run the application as administrator: Right-click the program you are using and select Run as administrator.
Change folder permissions: Right-click the folder, select Properties, then the Security tab. Click Edit and make sure your user account has Full control or Modify permissions.
Take ownership of the folder: If changing permissions doesn't work, go to the Security tab, click Advanced, and next to Owner, click Change. Type your username, click Check Names, then OK. Check the box to "Replace owner on sub-containers and objects."
Hope that helps,
~Jesse