hide url display in address bar

do you mean the whole adress bar? or just a certain site

You can disable the address bar and status bar in group policy if thats what you want.
NOTE: Group policy only exists on XP Professional.

Open run from the start menu and type in "gpedit.msc".
Then navigate to "user configuration\administrative templates\internet explorer\"

There are many options here which you can enable.
If you enable 'enforce full screen mode' then that will hide and disable everything except the status bar. To disable this as well open internet explorer before you enable the 'enforce full screen mode' option. Right click on a toolbar and uncheck the 'status bar' option. The status bar should dissappear. Then enable the 'enforce full screen mode' policy and re-open internet explorer.

Hopefully this will work.