Vista Defender vs Avast Home Edition???

[amigadave]

Does anyone have any recommendations regarding using Windows Vista Defender vs Avast Home Edition (Free version) to protect a Windows Vista 32bit system?

I have depended on Avast's free version for years on most all of my Windows systems and those that I have built for friends and family members.  When I got my replacement Dell system they gave me Vista Ultimate 32bit and I started using Defender as my only virus protection, but now I am wondering if I should maybe go back to using Avast.  

Edit: Should I use both???

[amigadave]

Thanks for all the advice.  I will use Avast and Defender together.  I will never ever use Norton or McAfee again and feel for those that do use it, but to each their own.

My ideal solution would be to ONLY run MacOSX, MorphOS2.x, a good flavor of Linux and AmigaOS3.9 (perhaps AmigaOS4.x and IcAROS someday) and run Windows only in a virtual machine on the rare occasions that I need it, without any internet or email access while running Windows.  Just have to sell this Dell tower so I can raise the money for a decently spec'd Mac desktop to sync with my MacBook laptop (and now iPhone).