I would observe that what you're trying to do is a really bad idea.
Having said that, you can use the File System security policy to grant access to files / folders using Group Policy.
You have conflicting requirements (and wholly orthagonal requirements to your question, too). If you're taking away "Administator" rights but giving users "Full Control" of the disk the OS is installed onto then you're just giving them an ability to get "Administrator" rights back (as well as installing software, malicious software, etc) by modifying OS files.
If you're trying to get users to stop being "Administrators" and start cleaning up your support procedures your best bet is to look at using "Folder Redirection" and mounting a political campaign of convincing users that their data will be safer, more secure, and more accessible by storing it in their "My Documents" folder (which you'll then redirect to a server computer).
There's no good reason to be saving files on a local hard disk drive. Any reason you can think of isn't good enough. Microsoft has done a great job, in the last few server / client OS releases, of providing mechanisms to store data server-side, have it available client-side even when disconneced from the network, and all the while keeping the data safe and secure.
It takes hard work, time, and effort to transition away from a culture of "everyone's an Administrator". You'll have to use tools like "Process Monitor" to beat your software into submission re: running as non-privileged users. If you can get it done, though, you will be a much better world re: recurring support cost, fighting "fires", etc.