how do I delete/hide the recently visited websites that drop down in
the search window?

Someone will ask you this, so I'll save them the trouble.  What
operating system (Windows XP, Windows 98, Macintosh, Linux, etc.),
what internet browser (Internet Explorer, Mozilla, Netscape, etc.),
and what search window (the one at the top, the one on the side,
etc.).  If you're using Internet Explorer in Windows XP, try going to
Start > Settings > Control Panel.  In there, double-click Internet
Options.  There should be an item near the bottom of the first tab
that is labelled History.  Click the button that says Clear History. 
Make sure all other windows are closed when you do, this, then click
Ok.  The next time you open an Internet Explorer window, the entries
should be cleared.  If you're using a different combination, post what
you have, and I'll put some instruction up for it.

Good Luck
Peter