Hi, i'm on vista x64. I'm using kaspersky 8. The fact that i'm on x64 make more secure right ? In which case i do really need to use an antivirus.
I mean for surfin on the net, ...

You still need an antivirus, any 32 bit Virus you get will run the WOW emulator and still cause as much damage as usual, and as i say to everyone who wants to run without protection - WHY?
proessing power and memory nowadays are extremely powerful, so do yourself a favour and just use one
P.S while your at it, run at least windows defender for spyware protection too.

Understood, yeah i have at least windows defender running

Here's to 10 years running without. Using Firefox or any browser with scripts disabled and similar, only allowing site's i trust, using the web is perfectly wo problems. Imho its better to configure your adsl modem/router and use some time on that so it suits your needs.
Check what ports you have opened and see how many you can close, things you dont need everyday.