Once you have a reliably clean installation, you really ought to get that safely backed up in a way which allows you to take the operating system back to that point. There are a number of programmes which will do an equivalent job, but I use Acronis True Image, which will make a compressed "Mirror" image of any individual hard drive partition. When your computer gets infected, you can boot from a rescue disc and replace the infected partition with the earlier clean copy. All you need then is to store your backups on some external medium.
As for programmes worth installing to help keep a new set-up safer and clear of junk, I asked for suggestions a few months back and got helpful suggestions - BLICKY to thread
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Quack!
GtD.