I forgot the link for IE 8 upgrade.
http://www.microsoft.com/windows/Internet-explorer/default.aspxIs the computer locking up with anything else besides internet explorer ?
Also I found this in a post when searching for the problem on google, the add-ons could be locking it up.
A few things you could check. First off, make sure you aren't loading a whole bunch off Add-ons into IE
Launch IE and go to Tools > Manage Add-ons
Disable anything that doesn't look right.
An alternative to that would be to start IE 7 in Safe Mode (ie no Add-ons get loaded)
Start > Programs Accessories > System Tools > Internet Explorer (No Add-ons)
If everything works find without the Add-ons you know it's one of them that is make a mess of ie.