Please help me solve this!

I just got a new computer and have been running Avast for virus protection, but some spyware has already slipped through my system. So, I have questions:

1. How do I get rid of it?

2. If I do, will it fix the task processor? If not, how do I get it to keep working so it doesn’t disconnect right afterwards?

3. I lose the Internet connection either immediately or within a few minutes. I did getYahoo toolbar set up after that, but that fixed the problem for about 10 minutes if it even fixed it at all.

My computer is slow to start up, but I’m hoping that will go away if I can clear the other problems. Other relevant information may be that I run Windows Vista on an Acer and have a didital cable connection through Comcast. I can’t seem to download anything anymore, either, but my brother does know how to edit or delete files or whatever manually before Windows starts up. He says that I have to find the process before he even does it, though, ‘cuz he is in college and doesn’t have the extra time to look stuff up. I don’t really want to do it myself…I heard you can mess things up badly…is there a way he or I can fix this?

Thanks in advance! I know this is an ID10t problem, for those who know what that means. icon wink SERIOUS Problem  Spyware.ISPYNOW, toolbar/task processor problem, connection problem, and Error 216? Sorry!
Oh, and I repeat this is spyware.ISPYNOW. that’s what Windows Defender is turning up.
Does anyone know what an Error 216 is, just out of curiosity?