changing browsers
To check or change the default browser, start Internet Explorer and go to 'Tools - Internet Options' and select the 'Programs' tab. Now tick the box labelled 'Internet Explorer should check to see whether it is the default browser'. To change the file association, run Windows Explorer (right-click 'Start' and select 'Explore') then go to 'Tools - Folder Options...' and select the 'File Types' tab. In the window with all the file types find the Extension entry for the URLs (type a 'U' in the field to bring you the first file type starting with 'U') -- also named 'Internet Shortcut' -- click the 'Change' button below, find and click the icon for Internet Explorer or Mozilla and click OK.
While being able to select either browser by clicking on the relevant icon, selecting the default browser for clicking on a link may entail a reboot for the setting to take hold.