Everytime i use google it redirects me to a scam site
something like free-spyware-scanner.org/secure2/?id=259.....etc
avg then popups with

free-spyware-scanner.net
exploit rogue spyware scanner(type 504)
c:/program files/firefox.exe
process id: 3220

every antivirus program i've tried picks up a trojan or two but never enough to get rid of this annoying virus.

Also.. for some reason my windows update wont update after i've restarted and only a portion gets updated...virus?
whats preventing me from updating my drivers?

i'm a total newbie with computers so any detailed information with completely help!

any help would greatly be appreciated