How do I move my offline Xbox Live gamertag and achievements to an online one?

I have an offline Xbox Live gamertag with a lot of achievements and a large gamerscore (considering I only have 8 games saved on my gamertag. When I got my Xbox to go online, they wouldn't let me use that one that was saved on my hard drive already. How do I transfer all of my progress to a new gamertag?How do I move my offline Xbox Live gamertag and achievements to an online one?
What you had before was not a Live account, just an account on your box. There is no way to transfer to you new live account, I have a live account and another xbox account on my box so that me and a buddy can play coop but that is about it. I do not use it other than that, sorry guy looks like you are going through all those games again. :(How do I move my offline Xbox Live gamertag and achievements to an online one?
That account you had wasn't an xbox live gamer tag, it was just a xbox 360 account to let you keep track of your achievements and such, but progress, like saved games I believe still might load up.
I know how it feels, but you can't, sorry.
u cant the same thing happened to me

inc.

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