[Jon12345]

How about something like this?

if ($vbulletin->userinfo['userid'] != 0 AND $vbulletin->userinfo['posts'] > 1000 and $vbulletin->userinfo['posts'] < 2000)
{
  // run code A
}
if ($vbulletin->userinfo['userid'] != 0 AND $vbulletin->userinfo['posts'] >= 2000 and $vbulletin->userinfo['posts']<5000)
{
  // run code B
}

Would that work? Are you allowed to use >= next to one another?