Is there any way to secure SAM(Security Account Manager) file from Windows in case of someone gets physical access to our pc and uses Ubuntu live CD to boot from cd and then copying our SAM file?
Encrypting your SAM File Is a good option however as you said you can not use Bitlocker so you can go for the boot time passwords that would prevent the users from changing the boot order and use an alternate platform to boot and access the windows resources.