The bottom line is - the internet is DANGEROUS out there. There are tens of thousands of viruses out there, with many more people trying to get into your computer. Ten's of thousands of people every year get their identity stolen THROUGH the computer, because they got a trojan that then recorded their credit card #'s when they were ordering something online.
If you are running windows, you become VERY vulnerable if you
1) Don't keep up with ALL the updates. This includes, windows, flash, java and acrobat reader [there has been recent attacks that automatically infect your computer if you are using a older version, even if you have ALL the windows updates]. Yes- there is the risk of the updates failing and messing up your computer (regular system maintenance will /prevent/ that most of the time) but you just have to deal with it if you want your system to be half-way secure.
These system updates are the "first line" of defense. They prevent most (but not all) of the attacks that automatically infect you by visiting a website (without clicking on anything) or opening a email (without opening the attachment). The reason they can do that is because there is a hole in the system itself, and you need to constantly patch those holes ("patches") when they are discovered.
The reason you are getting the "windows advantage" thing is because your system has been updating (probably automatically) and MS sneaks that in there. Eventually, you are FORCED to "prove" that your copy of windows is legit before you can get more updates.
2) Current Anti-Virus with a VALID subscription
I have seen so many machines that had anti-virus installed (when they bought the machine) but the subscription had run out and the software deactivated.
Go and CHECK to make sure it is actually valid. If you have not PAID MONEY for a new subscription (yearly), then most likely it is expired.
If you don't want to spend the money, then get the FREE version of AVG anti-virus (http://free.avg.com).
You will have to manually upgrade to the new free version they release every year or so [to keep you on your toes], but that isn't that big of a deal.
This will protect against traditional viruses that you get by opening attachments and downloading files off websites.
Also, make sure to remove the expired anti-virus first, as the programs can conflict.
If you have problems, you can download and run these specialized remover tools which will manually clean out all the files hiding on your system. I normally do it routinely as incompletely removed A/V software can prevent people from getting online, among other issues.
3) Spyware Software
This is the part that gets more complicated, because there is so MANY spyware programs out there.
Recently, there has been a trend of spyware pretending to be "real" anti-virus, and giving you all these fake warnings about your computer being infected. After clicking on it (and "installing" the program), it then extorts you for money before it will allow you to REMOVE the software [and/or make the messages go away] (and in the mean time, it installs trojans and all kinds of nasty stuff to track what your doing).
Most people notice when they are infected, when their computer starts running REALLY slow (because there is so many spy processes running, that it takes more computation time to do /that/ then it is to run your real programs). Another is when you get random pop ups for advertisements when you are not even online.
There is NOT one single program that can take care of all of them. Every few months, the programs that were effective fall back and new programs come into the scene that work better. I will just list the stuff that is FREE, as anyone can use it.
A) Spyware Doctor STARTER edition (Not "FREE" trial edition) - as part of the google pack (you can install only that and and uncheck everything else
A good solid program that runs scans every once in a while by itself.
B) Malware bytes - The free version only supports MANUAL scanning (so you should run it once a month or so).
It is very effective and fast
C) Super Anti-Spyware
The name makes it sound fake, but (so far) a lot of people have been having good success with it (including myself).
There is other programs that I would run myself after this, but they are more complicated to use and setup then this
ALL Computers die all the time - especially hard drives [yes, even mac's].
Make sure to back up your pictures and documents regularly (and whatever else you can't replace).
5) Be Suspicious!
If you are browsing a website, and a pop up randomly comes up and says you are infected (citing a name of a program you have NEVER seen before).
Be very suspicious. You would not eat pills from some random stranger you met on the street - it could potentially be poisoned.
Go and VERIFY who it is, and make sure they are someone safe to get stuff from before you go and download a program.
You go to a doctors office or a pharmacy to get medicine.
Don't EVER give out your password online. If a tech support person needs to get into your account, they will have a way to bypass the password check and get in directly.
If you DON'T like having to deal with all this, then get something else. Just because everyone else has a pinto doesn't mean it is the best car in the world. Get a mac or run linux (both of which have more stable systems and less viruses - for now, anyway). Windows CAN be safe and stable IF you are VERY careful with it and religiously stay up to date. It can be done, but it takes EFFORT to do so. Sometimes you need to run specialized software that is windows only (go and look - you can be surprised what has been ported over) and you just have to deal with it if you want to keep using that system.
A lot of people complain about mac's cost more, but if you INCLUDE the cost of time, energy and (occasionally) money to keep a windows machine secure (regularly getting it checked up by a professional), it can easily cost as much or more then a mac. I am NOT saying one is "better" then the other - I am saying it is a CHOICE, where there is plusses and negatives for BOTH and it is up to you to decide.
WOW! This got long really fast (hope this isn't too overwhelming for some of you), but there is a lot of stuff you have to be aware of.
Hope this will help some of you.
All of the above will protect you against 80% or so of the stuff that is out there.
It doesn't stop EVERYTHING, but it is a good start and some times the only defense you have is your head.