What I would do -
Get the machine running
Use IE to find Mozilla Firefox browser and download it
Make Firefox your default browser.
Get Microsoft's windows defender (free) if you don't have it and use the Software Explorer feature to remove all the trash from the start up file - including Internet Explorer if it's in there but probably not Mcafee.
Go to Microsoft's Windows Update and put the latest updates in your machine.
See if you can install a new version of IE (V7) to overwrite the existing version.
Get hold of Piriform's CCleaner (free) and use the registry tool to clean up the machine's registry
Allow Firefox to be your default browser - it has 21% usage
Good luck...
Peccavi
January 2009