I've been asking myself the CRT to TFT question for a couple of years, and am still delaying the upgrade. I'm using a 21" iiyama Vision Master Pro 502 CRT, and I have had this for what must be over 12 years! The thing is a monster and a real challenge to move any distance. However, I've got a friend who has a 24" TFT, and he agrees the images on mine make it pointless to change, so long as I've got the significant desk space needed for it. Cost me £525 at the time, but I've certainly got my money's worth out of it, which is a rare thing to say when it comes to computers. Don't have to worry about dead pixels either! I also know once I upgrade to a TFT, the chances are I'll need to be upgrading my monitor every 2 years.
I believe I read about some changes due regarding the way monitors will be connecting to PC's coming soon. Isn't the connector expected to change over the next 12 months? The term 'DisplayPort' comes to mind, but not sure where from. Perhaps someone can either elaborate or tell me I'm talking nonsense.
If the connector is due to change, might be worth waiting a while to see if this has any benefits, especially if your monitor change is not an essential one!