I removed the attachment as it appeared to be the master installer itself.
Regardless of your default browser selection McAfee utlizes IE for its function. If it's asking for IE7 (part of the published minimum system requirements) then I assume you have XP and it's SP3 I hope. Please install IE8 which is the maximum version for that OS..
If you have Vista, install IE9 and if you have Windows 7 or 8 install IE10. You don't have to set it as the default browser, just have it installed.
McAfee isn't the only process that uses it and as it's an important factor for security that your system is totally up to date, do that now.
Also I assume you got rid of the other brand using their removal tool as applicable?