[Kazun]

1.

$wcdate = "{0:yyyMMddHHmmss}.Z" -f (Get-Date).AddDays(-90)
$lldate = (Get-Date).AddDays(-90).ToFileTime()
$users = Get-ADUser -Filter "whenChanged -ge '$wcdate' -and lastlogon -ge '$lldate'"

2.

$users | Export-Csv result.csv -NoTypeInformation -Encoding UTF8

3.

Get-ADComputer -Filter * | Foreach {$_.Name} | Out-File result.txt

4.

http://forum.oszone.net/thread-280936.html

5.

Get-ADComputer -Filter "whenChanged -ge '$wcdate' -and lastlogon -ge '$lldate' -and Enabled -eq $false" | Remove-ADComputer -Confirm:$false