[64 bit] Need help to choose version

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http://ubuntuforums.org – Hi i have Samsung Notebook 3 NP505e5Z! CPU : AMD A4 1.96GHZ (2core) RAM : 4gb VRAM : 1 GB AMD HD RADEON shall i install ubuntu 12.10 32 bit or i should go for 64 bit, also i wanna utilize full hardware resource.... Is PAE works well in 32bit, if i go for 32 bit can i utilize my 4 gb? also can it support virtualization? The thing which resist to go 64 bit is application compatability and availability.. please suggest me friends.... :):) (Hardware)