Don't add anything that has virus protection built-in or has a firewall as that will clash with McAfee and possibly allow infection in.
Good things to keep handy on your machine would include what I have, Windows Defender (built-in to 7 but the installation of McAfee usually disables it so you'll have to enable it most likely), Malwarebytes Free, & perhaps SuperAntispyware Free.
Surf safely, be careful what you share with others and what you download.
Lastly keep 7 up to date at all times and that means it and all the software installed on it. It will hopefully already have SP1 (Service Paxk 1) installed as that has been out for some time now, and IE10 (7 comes with IE9 but IE10 is now current). Even if you use another browser by choice always keep Internet Explorer totally up to date as many processes, including McAfee, utilize it.
For some hints see the last link in my signature below.
Ex_Brit, So it's safe to run McAfee, Windows Defender, malwarebytes,
and Superantispyware concurrently w/o them interferring with
each other ?
As long as they are the free versions, i.e. no active protection, I've found no issues. Keep the others updated for use if anything unusual happens.
The latest scourge of ransomware is difficult to protect against however and most software gives mixed results whgen encountering it, just be extra careful and should you ever see evidence of it on your machine, do not touch anything except the power switch. Power up to Safe Mode and use System Restore to go back to before it happened.
If successful temporarily disable System Restore to get rid of it.
All these different things are still not 100% guaranteed to proof your machine aginst all that is out there, nothing will do that. Join a few reputable anti-malware websites and do some reading up on it.