Migrate SBS 03 to 08 or 2012?

Kind of depends on what you plan on doing about email
Going to 08 is going to be the simplest way,  You introduce the new server.  join the domain.
Make the new server a domain controller.  Also global catalog server, DNS server and DHCP (but don't activate it)
Move data to new server.  Migrate Email to wherever.
Uninstall Exchange from SBS
Move FSMO roles to the new server
Demote The SBS server and then remove from network
Activate the DHCP server on the new server

How many users are you typically talking about

Hey Rob

Thanks so much for the response - I will def check out the mig guides you suggested.  I lean towards VMware for Prod at this time - have 3 certs in it.  MS historically has had sec holes and although I guess I can just do the kernel install for the OS - still don't think they are ready for Prod yet.  In time.  It could be that I need to get more time into it, but for Enterprise level deployments I just feel VMware is far more mature. Let me know your thoughts/experience with hyper-v2, I will have to set up a test lab and get some hours in it.
Thanks again!

VMware is an excellent product and if that is your preference I wouldn't switch.  My logic when I switched from VMware to Hyper-V was one vendor.  When you have a problem you don't have one blaming the other.  I do feel Hyper-V is more than "ready for prime time".  I have two good friends in different continents who manage very large networks 100+ and 600+ servers.  Both were VMware supporters and certified but they are moving to Hyper-V due to deployment, security, and performance.  They feel Hyper-V does not have the full selection of big network management tools that VMware does, but the hypervisor product is as good or better.  They actually still use some of the VMware tools to manage their Hyper-V servers, but remember these are big networks.  Hyper-V licensing is also less expensive, however VMware is still an excellent product and I suspect will be around for a very long time.

I certainly don't disagree with Rob's comments regarding the age of 2008 as an OS.  And I was responding from my mobile phone :-)

You cannot migrate a domain directly from 2003 to 2012 or 2012 R2 to the best of my knowledge and so you would have to stick a temp DC in there at the 2008/R2 level first.  Unless there's a trick I've missed somewhere then Rob can set me straight;-)   And thus my comment about the "easiest" but I should have gone on to explain.

Hey Chris - I didn't realize that - so I would have to build a Win2k8 DC migrate to that and then move to Win2k12.

It has been over a year since I Have done one of these.
I believe I just created a new scope for DHCP and let the client do a broadcast to pull down the new addresses, rather than migrate over the DB,
I also think I just enabled DNS DDNS - populated itself -but feel like I might be forgetting something if the DC is still on the old box until I move over the AD Fismo roles etc.

So we can't go direct to Win2k12, a helpful piece of info.
Thanks!!

Ok...I stand corrected...slightly
You must raise the functional level of the SBS 03 domain first,
http://blogs.technet.com/b/canitpro/archive/2013/05/05/step-by-step-adding-a-windows-server-2012-domain-controller-to-an-existing-windows-2003-network.aspx

Guys

Thanks so much for all of your help!  Apparently once you raise the forest level to 2003 - you are able to move the fismo roles right over to 2012.  All worked well - thanks again!
Happy New Year to you!

Migration guides were very helpful RobWill was very helpful as well as others here!

Happy New Year!