How do I tranfer the data (like ratings and playlists! and not necessarily the songs) from my iPod to my iTunes?

My computer was completely refurbished, leaving nothing but my hard drive. I backed up my music and mp4 vidoes onto an external, so I still have all of my files. However, for those of you who put so much effort into their iTunes and love the benefits of it (and also on your iPod) – how do I transfer that data back onto my iTunes? Did I make that too confusing? I just want my ratings and playlists back!!!!!