For malware cleansing and maintenance, I suggest Malwarebytes anti malware (MBAM). You can run quick scans on occasion, and a full scan once a month (it’s free).
Defrag the machine once a month, you could use the built in defragger or try jery’s app.
Other than that, scan it with your eyes every couple of weeks. Look at the system tray, widgets and gizmos on your web browsers, your program files and spot check for anything out of the ordinary.
One huge tip that can save a lot of people time, headache, hassle and possibly a new computer now and then is this: Use only ONE anti-malware program. Choose one, stick with it, and remove any others that aren’t part of your OS.
The reason: If you’re only using one anti-malware, you know it’s okay to ignore any others, and that odd rogue anti-malware pop-ups you get can be treated as malicious adware or spyware or trojans, etc. Plus you build a confidence in trust in your selected program, and learn its ins and outs.
Anti-malware programs are such a widespread disguise for spam, hacks and viruses that you simply have to know what you can trust.
AVG, Avast, Malwarebytes and of course Norton are all good examples of programs you could stick with.