As This FAQ says if you have higher than 9.11 on your PC there is no issue upgrading with Mcafee installed.
Personally I would uninstall via the removal tool reboot installing windows 7 then reinstall. I feel that though a tad overboard is better. You must ensure you can access your account before removing Mcafee.
This is my personal opinion.. Of course some vista /win 7 upgrades backup the whole of the vista partition so you need to reinstall anyway which is what happened to me.