8GB ipod storage? not adding up...?

I have an 8 GB ipod nano, and from what I've gathered it should be able to hold about 2000 songs give or take. Supposedly on average 1 GB holds 200-300 songs. Now most of my songs are the regular 3.5 min to 4 min songs, but right now i have about 800 songs with 5 GB taken up... So if I say 200 songs per GB, I should still have room for 200 songs with the 5 GB. I was wondering if anyone had ideas about this? Would having artwork be a huge factor? Also I do have lyrics in SOME songs (maybe 20), would that be another huge memory-waster?