running all those programs will slow down the computer somewhat
no matter how fast the computer is that type of software messes with performance
remove all of it and notice how much smoother it is
many folk like the idea or running lots of scanner type programs
if you like that kind of thing, join wilders security forum or something similar
they will give you lots of advice on that kind of software and they are quite friendly
a fair bit has improved with windows 7 over xp as far as security goes
i do not think these programs are really necessary if folk are not doing silly things
like downloading from unscrupulous websites/ porn sites that require users to downloads codecs before you can watch your free porn LOL
an alternative to scanner type software, would be to look into virtual machines, sandboxing HIPS
which gives better protection than scanners
sandboxie is a popular program you might want to have a look at that it is easy to use
http://www.sandboxie.com/
returnil goes a step further down the virtualization route it is similar to deep freeze which is more well known but not free
http://www.returnilvirtualsystem.com/
Hips these might now be for everyone not so easy to use, they require some effort from the user
http://labs.360.cn/malwaredefender/
http://personalfirewall.comodo.com/
its not so much what you pay for with this type of software, but how much effort you are prepared to put in to understand how malware attacks the system
most folk do not want that burden and just want a one click solution scanner
most of these products offer the same free version, the same database of malware is used in both free and pro versions, but greater customization with the pro versions
if avast makes you feel safe continue to use it, i would not advise you to buy anything though, keep your money there are so many better things it could be spent on
malwarebytes does not give real time protection unless you pay for it, so it is of no use to keep it running, it is like a stand-alone scanner
it will not scan files automatically, you will have to start the scan manually
malwarebytes is a popular program lots of folk use it , personally i do not care for it, as it is just a scanner it does the exact same thing as an antivirus
but it uses a different database/blacklist of malware there is a huge amount of overlap coverage with these types of programes
maybe even 98% of the malware that malwarebytes detects is already detected by avast lol perhaps even 99%
peace