Typically, an LCD will not display the richness of colors and well as a CRT, which is why most designers still prefer a big monitor over a flat panel any day. So if you're doing any serious graphical work, you may be best sticking with your 17".
If that's not an issue, then chances are you'll like a flat panel better, but make sure to try it out in the store first. Make some text on the screen, adjust the font sizes, etc, and see for yourself how readable it is, do your eyes hurt, etc.
Also, it's nice to have the same image on a CRT next to the flat panel while you compare, so you can see if the colors look right and so on. And don't be afraid to adjust the settings... that's why they have a display model. (oops, pun...)
I've found most of the low-cost LCDs that I have looked at to be very disappointing, so I personally am going to wait until the better models become cheaper.
Just like a television, trying it out in the store isn't going to help unless you bring in your old monitor and computer to the store and compare them side-by-side, and you probably can't do this. The store will have different graphics cards and/or settings than you will have at home.
Also, the store will probably display very colourful photographs, rather than large areas of bright white or any fast-moving images. Very colourful photographs look great on all types of display.
It is hard to get a relative comparison to what you already have when you are in a store, because it all looks so "new".
That said, LCD technology is amazing nowadays. I am extremely impressed by a lot of what I see and if it weren't for the $$$$$$$$$$$, I would have at least one.
I must say that the colour, sharpness and contrast is very good on all current LCD displays.
Note: if you intend to play a lot of video games, or view DVD movies, you may want to do a bit of reading about it. Different technologies have different rise times. Later models of LCD displays have much better performance but it is worth checking it out. It isn't necessarily inferior to CRT, as a lot of people may tell you, but you have to make sure you're buying quality and it is does have a different 'look'. See if you can play a very fast video game on the display while you are in the store.