I think you'll be happy with what you got. The draw on screen tablets look amazing, unfortunatly I never got the chance to try one out for myself :(
If you're missing that "accuaracy" though, try using Adobe Illustrator, that program have some kind of auto refine lines build in. Like, you draw...
You should definitvly get a drawing tablet, it's like a whole new world. If not used only for drawing, you can also use it for making details really stand out in photos and what not.