Given that you tagged this with PowerShell, I will lean that direction with my answer. If you are have the ActiveDirectory module from the AD DS RSAT tools installed (using PowerShell 3.0 or greater here)
Get-ADGroupMember "CN=Group DN,OU=Group OU,DC=domain,DC=com" | ? ObjectClass -eq "User" | Get-ADUser | ? Enabled
If you want to recourse through nested groups, use the -Recursive
parameter on the Get-ADGroupMember
cmdlet.