As for the machine itself, install CCleaner and AVG (which IMHO is among the least intrusive of the A/V solutions)
IMHO these are among the last two Software Applications I would EVER use on a Windows machine... for many reasons.
I've been managing MS Windows based IT infrastructures for Small and Medium businesses since 1982 - when it was Program Executive...
Use Malwarebytes antimalware and MS Disk Cleanup.
None of my clients networks from BC to CA have ever been intruded or compromised in 30 years. Never! (Yes, Sonicwall's help but are not necessary.)
AVG is, IMHO, both overly weighty and ineffective and CCleaner is downright dangerous, unnecessary and overkill for most Home users.
The amount of IT infrastructure security information constantly coming from wannabe Net Admins on this site is predominantly misleading and dangerous....