If you are already using Google or Yahoo Toolbar you probably won’t want to use the built-in search box in Internet Explorer 7( though it's quite nice). There’s a quick registry fix that you can do to enable / disable this.

Open up Notepad and copy the following and save it to something “IE7_NoSearchBar.reg”.

             "Windows Registry Editor Version 5.00

 [HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Internet Explorer\Infodelivery\Restrictions]
 “NoSearchBox”=dword:00000001

Now  merge it into the registry by double clicking it.

thanks!

To disable copy this following code and save. After that merge it to the registry.

" Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Internet Explorer\Infodelivery\Restrictions]
“NoSearchBox”=dword:00000000 "