Keep My Computer Swift And Powerful And Without Viruses?

i recently bought a new computer with an installed Win7HomePremium. It is fairly good and these are a few of the properties:

-Intel i3 540
-4GB memory
-32bit OS

I was wondering what programs you can suggest me, I'm getting mixed messaged from all kinds of people on what software i should(n't) download and its getting annoying.So a general question could be what programs u suggest me to use in order to keep my computer swift and powerful and without viruses? It should be noted that the person who recomended these to me has a computer since 2003 which she uses the progs to clean it every 2-3 days. And it's working great, or so she says.So in addition it could be awesome if anyone can give me ONE answer instead of the mixed opinions - whether or not should i clean my computer by running such software and if so which ones and how often? Also is it true that IE is regarded as a problematic browser? I switched to Chrome without erasing IE and so far it's fairly good (except for random slow downs and sites not opening , and especially having trouble being on facebook too long )One more question that i believe , out of anyone, you can help with: By default, the folders are presented in list-like formation and it's kinda tiring going over every folder and ordering them differently. Can I do anything to make all of the folders sort in a different way? and possibly one of the more important ones - my technician told me that if i were to format my PC, and i'd have at that point over 200GB taken (out of the 500 i have ), the computer will erase some of MY files as well. If that is true - that's completely stupid. Is it ? And if so what should i do? (have one partition)BTW I often see all kinds of short versions of words here, like BSOD, SSD, UAC and what not. It would be very nice of you, considering many of the readers don't know these terms, to simply write the full word. It doesn't take much time.