Do i need to add antivirus to windows 7

Download Microsoft Security Essentials (Google it). It provides very good protection and can be ignored once it's installed.

avira free antivirus

malwarebytes free spyware scanner

pc tools firewall plus!

ccleaner and this is a great free package!

^+1 for avira. The free version has a pop up every time it updates, but the detection rate is quite good.

CCleaner, Defraggler, Firefox are a must in my book.

For firefox, download the AdblockPlus and NoScript adon's for better security/user experience.

Just because Win 7 is new doesn't mean it does not need an anti-virus program.