How do I calculate TV size with aspect ratio and diagonal inches?

[tahoedrew]

I'm in the market for TV's and I'm debating between a 36" 4:3 Tube TV and a 32" 16:9 LCD. I'm not sure which one I'll go for yet, I'm still "weighing" the decision (which is about 180 lbs or so!).

What I guess I really want to know is what would the measurements of a 16:9 DVD be on a 36" 4:3 aspect ratio TV?

Thanks for the knowledge!

~A