Actually, you can do something similar to password protecting a folder in windows 7 by using its security features. If you are an administrator and have multiple accounts set up in Windows 7, then you can block few important folders so that they cannot be accessed by other users.
1. Right-click your target folder to select Properties. On the coming up window, select Security tab and click Edit to pop up the following window.
2. Select the user from the list whom you want to deny access to a specific folder under "Group and User Names", and check the Deny checkbox next to Modify .
3. Click "OK" and then click "Yes" when a Windows Security window will pops-up. Click "OK" again and you are done. Now the specific user that you selected from the list will be denied access to this folder.
Every time the blocked folder will be accessed, it will ask for administrator password. Therefore the folder will be locked permanently unless you don’t remove the lock yourself. But this method is not highly recommended if you want to a password protect folder. The best method is to seek for third-party folder encryption software, like Truecrypt. With this most popular open-source tool, you create a single file on your computer's hard drive that is encrypted. If someone looks at that file all they see is random data - there's no way to know what that file contains.