You are not happy about your 20/30/40 D because?

I have a 20D and I'm perfectly happy with it's abilities to take great picture. I wonder why do you even want to upgrade to a 50D? or even a 5D?

FF doesn't have much of a advantage. With canon 10-22mm, you can take great wide angle pictures.

I'd rather spend more on glasses, books or software.

Let me know why do you want to upgrade from a 20/30/40D to a 50D or 5D.