Libraries and iTunes and AppleTVs, Oh My!

[lurk]

I was wondering if anyone had some great ideas about how to split up my iTunes library. My problem is that my laptop only has a 100 GB hard drive, while my Apple TV has a 140 GB hard drive. Now I do have an external hard drive to use for backup purposes that is 500 MB, and conceivably while this hard drive is attached to my laptop I could have a similarly sized iTunes library. The big problem is that this is terribly inconvenient, I like the fact that my laptop is a laptop and I’m not going to be lugging around that extra hard drive all the time.

Ideally I would like to store all of the video on the external drive and have it sink while it is attached, but not have problems when the external drive is not present. I have tried several variations on this and they can’t really settle on one that works well. I hope I’m missing something obvious, so please tell me how you would solve this problem.

Thanks!