In Active Directory Users and Computers expand the local domain, if you open your company users OU, depending on were you created your users.
Right click on the user’s account and select properties to open the users properties dialog box
On the Account’s tab under Account options field
You can select the check box “User must change password at next log on”
select apply and OK
Note that this option is not permanent, as the option is disabled once the user has successfully changed the password and logged on
It is also worth noting that if you want your users to have a ‘random’ password that any domain password settings are done through the default domain policy in Group Policy Management. Any change made here will affect ALL users. It is possible in 2008 to set up multiple password policies but its a bit of a nightmare working out how many milliseconds from the year 1600 it’s been. No i’m no kidding.