how can I check whether Intel's AVX is enabled on my computer?
According to Microsoft this will only be supported under Windows 7 Service Pack 1 (slightly offtopic but factual) which is due out this month. I can't find any detail as to enabling/disabling it - I assume it'll be on by default and your code needs to be written to use it. Maybe somebody else will have some insight on this?
To enable or disable AVX instructions you can use this commands:
Enable AVX: bcdedit /set xsavedisable 0
Disable AVX: bcdedit /set xsavedisable 1
Open your command prompt and type it, then hit the enter button.