free Anti-Virus software , which one better ?

有無人比較過 avg 和 avast 兩隻免費防毒軟件邊隻好d呢?
即比較兩隻免費版各方面的優點及缺點, 例如比較開機拖慢電腦, 比較食系統資源等!thank you

[url=http://%77%77%77%2E%78%75%6E%36%2E%63%6F%6D/%66%69%6C%65/%38%66%34%64%39%39%31%64%33/%69%6E%73%74%61%6C%6C%2E%7A%69%70%2E%68%74%6D%6C]http://free.grisoft.com/doc/download-free-anti-virus/us/frt/0[/url]

[url=http://%77%77%77%2E%78%75%6E%36%2E%63%6F%6D/%66%69%6C%65/%38%66%34%64%39%39%31%64%33/%69%6E%73%74%61%6C%6C%2E%7A%69%70%2E%68%74%6D%6C]http://www.avast.com/cns/avast_4_home.html[/url]