That's right, you are not the global administrator, although that account can be turned on.
You can set UAC to Never notify as long as you have a good anti-virus , spyware detector, and/or personal firewall to avoid the constant nagging.
For folder permissions, right-click on the folder, choose properties, click the Security tab, click the edit button, select your username and check the box for Full Control. If your running the 32-bit version, there was a patch for this from Windows Update.
If your using a leaked build, well then...good reason why you should stick with the original RC from MS.