^ ^ This.
Burbles, do not surf the net in admin mode, particularly if you are using Opera rather than Firefox.
It's warnings aren't as good even though it is very good in other respects.
The missing service pack is going to be one of your problems I suspect. Being a year out of date for security patches is not a good thing.
The reason I asked of you had read the help file for Kaspersky is because if you have a legit copy of it they will provide you with backup. You can submit a report on your machine and they'll tell you what is wrong with it.
Personally I wouldn't turn it off because I've been running Kaspersky, in conjunction with all the latest security patches, for the last two years and it seems to catch everything because I've never had a moment's trouble. You need to keep Kaspersky updated on a daily basis
as well as keeping Vista updated. Do not turn off automatic updates for Kaspersky. It should run every time you access the net.
A registry cleaner is worth running occasionally, as Biax mentioned. I can dig out the link and instructions for the one I use.
If your brother is still hanging around and surfing porn you can install Sandboxie. This quarantines everything that is downloaded from the net. Nothing gets outside the sandbox unless you go through the contents and specifically move it out. When you clear the sandbox everything in it is thoroughly wiped. Sandboxie: http://www.sandboxie.com/Registry cleaning:
This is a very good article that tells you all you need to know and gives handy links.http://www.hardwaresecrets.com/article/298/1Kaspersky: http://www.kaspersky.co.uk/
Note this part: "Kaspersky Lab is now offering free online courses for personal and business products. The courses help users understand how Kaspersky Lab products work and give instruction on how to use them effectively. Click here for more details"