What does /x/ use to keep their PCs tiptop?

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I've found programs to prevent malware, spyware, viruses, trojans etc but what about getting rid of any I have?
I had a soup of programs I'd use to detect issues but it wasn't enough. My computers were still fucking up.
Some of the programs would find them but wanted me to give my first born to actually identify and remove them. That or they wouldn't find all of the issues.
I'm willing to pay the <=40 for the programs I've found to prevent future problems but right now I need to get rid of what I already have. Whatever they may be.
My PC's both take ages to start up and I absolutely cannot do shit for at least five minutes or everything will lag and freeze. I'm guessing the startup process having something to do with it and maybe too many programs executing at startup or even the wrong ones (i.e. badware) It often freezes and shit and is just slow a lot of the time. Hell, at times right clicking take minutes or will freeze :,D There are times when some of my most uses programs act like they're gonna run but then kind of just..don't.
I tried to reformat after backing up my shit onto my external hard drive (which is actually just a HD from my previous computer nigrigged to my current PC but hell it works)but it just..failed? For reasons beyond me it just simply didn't work.
BestBuy has a bunch of services they offer for this sort of thing but really shitty reviews. Pathetic reviews. On their own site.

So /x/
What do ya'll use to keep your computers clean and get them clean if it gets fucked off?

Just a note, I'm trying to buy wins7 os since I forgot my ex pirated the OS I have on my computer (It was his but I got it from him when he upgraded so in my defense, I didn't know) So any programs that fuck up pirated OS's please no.