Upgrading ISA 2000 to 2006

[Cmd.exe]

We're currently running ISA 2000 on our 2003/XP network.
I have purchased an ISA 2006 licence, but I have read that you cannot upgrade from 2000 to 2006.
Is this true?
If so, can i install over the top anyway, or am i going to have to do a clean install of Server 2003 + ISA 2006 on the server over a weekend?

[Ric_]

There's no need to re-install Windows. Initially, I would try installing to see if an upgrade is offered. If it isn't possible, export all your rules, etc. and uninstall ISA 2000. Once you have installed ISA 2006 you can import the rules again (if they haven't changed the way import/export works too much between versions).

[Cmd.exe]

Thanks Ric_, i'll give that a try.