iPad is synced with another iTunes library. Help.

I haven't backed up my iPad with iTunes in a long time. I'm now trying to back it up, particular the apps on it.

The problem is when I plug the iPad in and launch iTunes, I get this message saying my iPad is synced with another iTunes library. My only options are to "erase and sync" or cancel.

I don't know what is in that "other iTunes library" and I surely don't want my iPad erased. What is this other iTunes library and how do I get rid of it so I can backup my iPad without it getting erased?

Thanks.

1) Make sure you are running the most current version of iTunes. Should be 10.1 at least.

2) Make sure your computer is authorized for you iTunes account. In the Store menu choose Authorize Computer. If it already is, it will tell you so.

3) Make sure you are logged into the iTunes store. You're Apple ID should be displayed near the right top corner of iTunes. If not, it should say Sign In (or something like). I'm not certain this step is necessary, but it won't hurt.

4) Now, when you plug in the iPad hit cancel when it wants to sync/erase/whatever. Go to the File Menu and choose Transfer Purchases From. . . or you can right click on your iPad under the Devices list and choose Transfer Purchases.

5) Double check to make sure all your stuff is now in iTunes.

6) If, and only if, all your apps, music, movies, and books are now in iTunes it is safe to sync and or backup your iPad.