Kaspersky has caused me nothing but problems on PC I have installed it on. I find it really messes with certain registry settings. McAfee is a gigantic memory hog. Only Norton is worse. If you want a top-flight all in one solution that is non-free, get yourself either Eset or BitDefender
Antivirus Software - Eliminate Spyware and Adware with ESET NOD32 Antivirus Antivirus software - BitDefender - The future of security now!
I have used both, and they are very good and
very light on resources (a must for me).