Activated iphone to wrong restore point - can I fix this?

Just upgraded to an iphone 4 and stupidly activated this phone without syncing the old one today. I use more than one pc and thought it was already done...

I would love to get some info off my old phone - mainly the text messages which are now missing from the last month.

I cant seem to find a way of doing this. I have the old phone with the current sms messages on it - tried syncing it to itunes but doesnt seem to transfer them to the new handset when i sync that.

Is it possible to redo the activation or change the restore point?

Thanks in advance!