QUOTE(Toastburglar @ Mar 4 2008, 07:32 PM)

I already have a SSN because I previously worked in the US. When I cross the border and activate my CR-1 visa, can I work right away? Is there anything else I'll have to wait for?
Yes, you can work immediately, but you'll have to use your immigrant visa to prove employment authorization until you get a permanent resident card.
You may apply for a new SS card which won't have the restriction legend on it and can be used alone for employment authorization.
You can ask for this to be done for you on the DS-230 application itself, but even so, you should still take your visa to an SSA office shortly after arriving (5-10 business days suggested) to check on the status of the new card or apply for it again there if the DS-230 request didn't make it (and will not make it) to SSA.
I thought the check box on the DS-230 application is only for new SS numbers only?