Had to get new operating system

About two months ago my dad had to get a new OS for our computer because my brother got a virus. The virus he got us was the wonderful winigurd virus. He downloaded a free trial of winiguard antivirus.
It gives you fake alerts to try to scare you into giving the people who made it money.
here is a list of things it did
1. Hijacked windows seceurity and AVG
2. gave fake virus warnings
3. terminated any scan made by Anti-Malewarebits
4. It is an extreemly polymorphic virus
5. It has its own attack system
6. permanitly disabled software updates for anti anything
7. It apparently has a Logic Bomb (thank God we did not trip it)
8. while getting it out it attacked our router and shut it down to the point that we had to get a new one.
9. It has a self repair program to repair the self repair program.
10. it apparently steels credit cards (did not happen)
11. It deeply roots itself into you system 32 folder.
12. causes everything to run slowly
13. demands $50 to do nothing but give you more virus (did not happen)
14. litteraly screwes over you computer.
And that is just the confirmed things it does.

The worst part of it all was that I had made so much progress in Spore at about the time my brother got the virus.:(

Viruses are Window's biggest problem. I hope you replaced it with an operating system that can't get them. *Nix system are immune to viruses because they are better designed. In Microsoft windows, the security system is a separate system, and can be shut down. On *Nix systems, the security system is embedded into the file system, it can't be shut down or worked around. If you don't own a file, the OS won't give it to you and if you shut down the file system, nothing can be read, not even by the virus.

Ubuntu is the OS that you want. It's got a Linux kernel, and a full suite of applications that are equivalent to their windows counterpart for the average user.