cant get newly purchased songs onto ipod

I recently moved my library onto a new computer. But now I cant get the 5 songs I purchased today onto the ipod. I tried both automatically and swithing to manual, but when I try to drag and drop I get a black universal "no" when I try to drop a song into the ipod.

Also, because I used the ipod as a storage device during the transfer, I now have an extra 1.5 Gb file just camping out on my ipod. How do I delete it?

I like my library on my computer as it is at this moment and so if erasing and resetting the ipod is an easy solution that will clear the memory and reload my library, Im ok with that, but I dont know how to do that either (if you think its a good idea).