U should not hope for the av to secure u from the virus…
not all spyware, virus, adware and many more threats not been detect by all av…
some av that detect one type of virus but the others not…
the best thing using av with other security software such as firewall and antispyware…
I suggest u to use kaspersky as it has good detection and good for a normal user who didnt know nothing…
Avast also good but not good enough to prevent any new virus…
unlike kaspersky…there rr some program that secure the computer from been damage by new virus before detect in the virus database…
but it just for simple virus…if u not update all av will no good as some virus like virut/vortob also can infect ur av
the important is to keep your computer up to date…

for me…avast is good…but if u not doent know about computer then i prefer kaspersky…it more secure with it but u need to pay for it…