iTunes won't sync correctly with external hard drive

I have long kept my music on an external hard drive and had absolutely no problems with adding files to my iTunes library. Whenever I added songs to iTunes, they would automatically be copied over to my external device (a Seagate Freeagent 1TB USB External Hard Drive) everything would be fine. I could erase the song data remaining on my notebook without any problems.

But, after recently upgrading to Windows 7, I'm having some trouble keeping everything organized. I did a clean install so I had to reinstall iTunes, and upon doing so I specified for it to access my library from my external device like before. It does that just fine, but when I add songs to iTunes, they don't copy over to the hard drive, and when I consolidate the files, all of my songs get copied onto my notebook hard drive.

Is there a fix to this? Something I skipped when telling iTunes where to get/keep my music? I want to be able to add songs to the library and have them copy directly to my external device.