Migration assistant question

In a few days I will have my hands on my new mbp.
I think of using migration assistant.

I wait all my settings (& files?) to be transferred to my new mbp.

I want to ask here, what should I expect as far as it concerns the osx itself.
I mean that I have 10.6.7 in my current-old mac, and the new one will have the 10.6.6, because that's the osx apple used in mbp when the machine was shipped.

But, I want to ask about what happens to osx version itself. I want to mention 2 things:

- The 10.6.6 of new mbp has some 'internal' settings that support 'trim' for ssd disks. The 'other systems' 10.6.6 do not have it. Even 10.6.7 does not contain these settings. I think I read these things in appleinsider.

- A few days ago apple gave as 10.6.7. There are two versions of 10.6.7: one for all macs, and one for the new mbp's with thunderbolt.

So, what happens to osx established system of the new machine, when migration assistant transfers all these things from a machine with 'newer' osx version?

Will I lose the 10.6.6 system shipped with my mac that recognizes 'trimm' support for ssd disks?

Does the osx version of the target machine remains as is?

What do I have to expect? What I should do?

 

Of course I will do so. I 've already downloaded the appropriate update file.

All I want to know is to assure that the new mbp will not be update with the 'wrong' 10.6.7 system, due to migration assistant process.
I want to transfer all my settings from the old computer to new one, so that I will not have to setup every single thing from the start, without transferring the 'osx' new version from the old to new machine.

Can I choose not to update osx during the migration process?