Outlook client configuration after SBS 2008 migration

Nope, you will need a multi-domain cert (SAN) first of all for autodiscover to work properly.
Here is the process I go through with SBS 2008, I have found this setup and configuration to be the least painful, hope this helps. Make sure if you get a cert from someone like godaddy to follow the instructions on installing the intermediate certificate and download the cert for IIS 7.

Even though in SBS 2008 a Self-Signed Certificate is supported for use with domain-joined Microsoft Office Outlook 2007 clients and Outlook Web Access, I do not recommend long term use of the self-signed certificate for any purpose other than encrypting communications between Exchange 2007 servers within your organization. I recommend that to support many, if not all, of the Client Access server features such as Exchange ActiveSync, Outlook Web Access, and Outlook Anywhere, you obtain a certificate from either a Windows PKI or a trusted third-party CA and make sure that this certificate is imported using the SBS Console SSL Certificate wizard.

When you run the Internet Address Wizard you need to just tell it you already have a domain and you will manage it yourself. This should let the wizard complete and configure exchange with the proper smtp addresses. I also never let the wizard configure my router. I'm usually a wizard guy but this is one area I feel more comfortable in setting up the router myself and it usually fails if the router isn't upnp.

When it asks for your external address i would use the default of "remote.externaldomain.com"
Then create a multi-domain certificate from godaddy or someone like that. The configuration of the Subjective Alternative Names (SAN) would be something like this:

remote.externaldomain.com - If you didn't choose this as your primary name.
sbsservername.internaldomain.local - this would be your internal sbs server name.
sites.internaldomain.local - this will work for your internal companyweb
autodiscover.externaldomain.com - This will help Outlook Anywhere and Activesync.

There are others you could use but these are the basics.

You will need to modify your existing external DNS with these records that are externaldomain.com I prefer to use a wildcard * to redirect everything that is not specified. The wizards will configure the rest for internaldomain.local.

This normally takes care of internal issues and external issues.
Here is the process I go through for disjoining/joining workstations:
1. login to the workstation (ws) with the local administrator account.
2. drop the ws from the domain and reboot.
3. go to documents and settings folder and copy the most current profile for the user that logs into this machine to a safe place. The date modified should tell you which one that is.
4. right click on my computer and click on properties then the advanced tab and then user profiles.
5. remove all users except the local administrator account.
6. go to control panel and local user accounts and remove all except local administrator.
7. open IE and go to http://connect follow the wizard. it should be pretty straight forward.
This will give you a clean install of the user profile for the new domain without pulling any old crap (that is the technical term:-)) from the user profile. Trust me it is usually not worth it. You can then copy most data back over to the proper folders in the new user profile including the nk2 file.
Hope this is helpful and if you need further clarification on any of the steps above or I have misunderstood something please don't hesitate to elaborate.  

Could you address my actual question instead of pasting in your usual stuff?  You already have this generic answer to another question I had.

I'm sorry if I didn't address your issue directly but you were asking for multiple answers to a complex situation, but I wouldn't consider my response generic, unless you consider the answer is always the same for the same question. Also, I didn't catch the fact that I had posted to another question of yours. My answers are based on my experience and best practices that I know work over and over again.
If you have one overriding specific question that you would like to ask then I could address that one specifically.
 
 

I have 20 computers on Outlook 2003 and 20 computers on Outlook 2007.  Currently, I'm on SBS 2003.

I'm migrating to SBS 2008.  

What non-manual methods are there for switching the Outlook client settings for the new SBS 2008 box?

not the answer I wanted, but I guess it is what it is.  Separately, I investigated the Swing Migration option at sbsmigration.com which I decided to go forward with.  When done properly, a swing migration puts you on your new server with the relative identity as your old Exchange/SBS box.  In the way, the clients don't really know you changed servers.  From their point of view, the server is the same as it always us (same name and location).