I would uninstall IE7.
installing Internet Explorer 7
To uninstall Internet Explorer 7 and restore Internet Explorer 6 when using Windows XP or Windows Server 2003
1. Click Start, and then click Control Panel.
2. Click Add or Remove Programs.
3. You might have to CHECK the box that says SHOW UPDATES
4. Scroll down to Windows Internet Explorer 7, click it, and then click Change/Remove.
If you cannot find Internet Explorer 7 in Add or Remove Programs, click Start, click Run, type
%windir%\ie7 \spuninst\spuninst.exe
(I added a space after ie7 so you could see the whole line.)
and then press ENTER.
For more information, check this page at the Microsoft website. http://msdn2.microsoft.com/en-us/ie/aa740486.aspx
If you have further trouble, you might try the RESTORE thing in the System Tools folder and go back a few days before you made this terrible mistake.
Good luck and Happy Computing!