Registry is treated exactly the same as the file system, each key and value has its own permissions so that each user can only view or modify only a subset of it. Normally every user has read-only access on HKEY_LOCAL_MACHINE and HKEY_CLASSES_ROOT but full read-write permissions on HKEY_CURRENT_USER. Administrator have of course unrestricted access to everything.
Like any other file, you should user normal permissions and different accounts to protect sensitive parts of both registry and filesystem.
Only to part of it, according to the permissions given to each one.
The built-in registry editor (regedit.exe) always request admin access when using the default setup, but it's not strictly needed. Admins have access to everything, but plain users still have control over their own settings.
My Computer
At a glance
Windows 7 Ultimate x64Intel Core i7-740QM8 GB DDR3NVIDIA GeForce 330GT
Computer type
Laptop
Computer Manufacturer/Model Number
Toshiba Sattelite A665-S6092
OS
Windows 7 Ultimate x64
CPU
Intel Core i7-740QM
Memory
8 GB DDR3
Graphics Card(s)
NVIDIA GeForce 330GT
Screen Resolution
1366x768
Hard Drives
Samsung 840 SSD 500GB
1TB USB3 external HD
Cooling
Coolermaster Notepal U3 notebook cooling pad
Internet Speed
3mbps ASDL
Antivirus
ClamWin 0.98.7
Browser
Opera 12.17 x86 (main), Firefox 38 (sec), IE11 (last resort)