I really appreciate the replies.
Indeed, I was really thinking about getting a flat 21" TV. I had heard about this issue with the light guns, but I wonder how problematic is it. Does it render the games unplayable?
I ask this question because, in fact, one of the main reasons for me to get a CRT TV is to play some Saturn and Dreamcast shooting games on it.
Once again, I am very thankful for all the support.