I want to store a number of TV shows purchased on ITunes on my Ipod, but erase them from my hard drive to save disc space. The problem is that I deleted a bunch of shows from my computer and the next time I synced up my Ipod, it auto deleted all the shows. Can anyone tell me how I should set my preferences to do this? As always, thanks in advance.
Yeah isn’t iTunes great?
You need to turn off AutoSync. This should help.
Thanks, I’ll check it out.
Mild hijack, I guess, but could one subsequently transfer the file from the iPod back into the computer?
Not if it’s been deleted from the iPod already, as the OP said it was.
My bad; let me clarify: Assuming one succeeded in keeping the files on the iPod while deleting them from iTunes (as the OP was asking how to do), could one subsequently transfer the files from the iPod back into the computer at some point in the future - or onto a different computer, for that matter?
Yes, there are plenty of programs that will copy files from an iPod. Here is one, iDump. 
Harder to find are programs other than iTunes that let you copy files TO a late-model iPod. I used Yamipod before, but it doesn’t work with new iPod Nanos.
The best way to handle the issue in the OP is to delete (or better, move to external storage) the underlying files, rather than deleting the files within iTunes. The response from iTunes will be to place an exclamation mark next to the entries, but it will not delete them from your iPod. If at some future date you decide you want the files back, it’s easy enough to merely copy them back where they were and iTunes will carry on as though they were never gone.