Just to clarify this a bit, the problem with Active Directory is that
nothing can really image it the way most people think of Ghost imaging where you can restore the images after a long period of time.
The main problem is that some of the most important content in an AD database - the password information for member workstations - is constantly being modified. As part of domain security, member machines regularly generate new, random domain passwords for themselves (NT4 used a two-week cycle by default for this and if memory serves the default is similar in AD systems). As a robustness measure, when they do this most machines remember the previous password they had and try that if the domain controller rejects their recent one, so if you're very lucky an AD snapshot might be usefully recoverable for one password-change cycle after it was taken. After that, enough of the member workstations will be one their second password change and if you restore the AD database, member workstations won't be able to authenticate to it until they are rejoined from scratch.
There's nothing wrong with using imaging on a Server 2003 system for bare-metal restore - there's nothing in the base OS of server platforms that Ghost clients have any trouble with - but the AD database needs to be treated just as that, a database, and needs to be backed up on a fairly frequent schedule. GSS doesn't come out of the box with the right kind of specialized tools for doing a good job of that, just like it doesn't for Exchange or SQL Server.