Outlook 2003 .ost file disabling

Hello,

I have a smal network with 1 Exc. server 2003 and 7 clients using Outlook 2003 on Win2K.
I would like all of the clients to use Outlook 2003 but I do not want the files stored on .ost files locally (I would
like the good old fashioned way Outlook 2000 worked with Exchange server accounts - e.g. all the files stored on the server)
The reason is that recently I had to set a client computer to workgroup mode and back again to domain member and all the user's emails/contacts files were lost.... I found out that they were moved to a .ost file, but when I imported it all the user's contacts were lost.
So after that I want to disable the .ost file in Outlook 2003.


Thanks
D.P.