Fault tolerant for SBS Server 2008

Good question, we'll wait for demazter or alanhardisty to answer this one...

I am pretty sure you can add another DC to the domain and add another Exchange server to the org, but as far as I know, clustering is not supported on SBS, so you are limited to LCR

You can add as many DC's but you cannot add another SBS or in the case of SBS you cannot add a "fault tolerant"  Exchange server. You can use outside Exchange backup services like www.exchangedefender.com
If adding DC's SBS must still retain all FSMO roles

Add an additional server to an existing SBS 2003 domain:

If the new server is a newer version such as server 2003 R2 or server 2008 you first need to run adprep, on the SBS, from the new server CD set to "extend the SBS schema".
If the new server is server 2003 R2adprep  it is located on the second CD under \CMPNENTS\R2\ADPREP\
If Server 2008 see: http://www.petri.co.il/windows-server-2008-adprep.htm

-Make sure the SBS is fully up to date with all patches and service packs, which makes it more compatible with the new O/S's (2008, Vista, Win7)
-You need to create a computer account for the new server, on the SBS, using the wizard located under server computers in the server management console of the SBS
-If the new server has more than one NIC, disable all but one while joining the domain. Once completed you can enable others
-Then point the new servers DNS only to the SBS, and join the domain using the wizard  http://SBSname/connectcomputer
-If the new server will not join with connectcomputer (I don't believe 2008 will yet), add it manually under My computer properties / computer name / change, and then in Active Directory move the computer from the Servers OU to the MyBusiness/SBS servers OU
-If you wish the new server to be a domain controller, now you can run DCpromo on the new server. You must use integrated zones when working with SBS. (there are different options in the wizard, just choose defaults and integrated). I would recommend at the same time installing DNS.

-If the server is going to be a terminal server (DC and TS is not recommended) you can add the Terminal Server and TS Licensing Server roles now.

You may want to review the following as well:
Add and Manage Additional Servers in a Windows Small Business Server Domain
http://www.microsoft.com/downloads/details.aspx?FamilyID=6f4015f2-7606-4eaa-828a-00b8df6bd999&displaylang=en

Thanks a lot. I am OK with adding the DC. But is it possible to set up Exchange 2007 replication between the SBS Server 2007 and the new Server 2008 with Exchange 2007 Server installed?

Thanks.

Not really. In large corporations with Exchange only (not SBS) there are ways to do so, and you can also set up multiple virtual servers in a "cluster" that will seamlessly connect users to the second server without the clients even knowing. But these are quite expensive solutions and intended for large corporations.
The best protection with SBS is a good backup.

You can also add a third party service such as www.exchangedefender.com
ExchangeDefender becomes a middle  man for your server. E-mail is routed through their servers and you gain the following features for about $2/mailbox/month:
-Act as a smarthost, protecting you from mail relaying and blacklisting
-Guaranteed no viruses via e-mail
-Excellent spam filtering with very good user control
-Back-up MX service that retains any incoming e-mail if your server is off line (up to 7 days) which is then forwarded to your server as soon as it is back on line
-archive of ALL e-mail sent and received for 1 year (longer for additional fees)
-Archived e-mail is accessible through Outlook Web Access 2010, and this site can also be used to access recent mail and reply if your server is off-line.

Thanks for the suggestion. But we would prefer to have a second server in-house as the backup. Is that any way to set it up?

Thanks.

Thanks!