How do you lock a computer, so that it displays just the internet?

put all your files in a mega folder and folder lock it or use softwares that would hide all your files with a password. to get these softwares google them there are hundreds of them out there free.timer is just an add on if you use firefox for your default browser. this add on gives no of logins time of each login and many other features just get it. ll

this is what's known as a 'kiosk mode' pc because it is running nothing more than a web browser and it's intention is not to be used for anything else by the general public:
http://www.emailarms.com/products/internet_kiosk.html

a dedicated (and likely paid-for) kiosk software will likely be required because no matter how much 'tweaking' you do to try and keep people out of all the other stuff there will wlays be at least a dozen weak points for any computer-savvy person to exploit - windows is full of holes.

Not to put a damper on any of your plans, but in Windows you can do something cool.

You can set up a guest account (or an underprivileged account of some sort) and log on. Then log off. Then log on as an administrator, go to C:\Documents and Settings\xxx where xxx is the name of the guest account you made. There you should see a file ntuser and underneath it will show DAT file. Right click ntuser and change it to ntuser.man

Changing it to the .man at the end means no matter what settings are changed on that account, when you log off they are reverted back to the original settings. I have use this as a guest account in my house, so when friends screw stuff up, I just log off and log back on and it's a fresh new desktop for them.

If you need help let me know.