I had that thought in mind as well, when deciding which components to buy to build my computer, and what monitor I would use. I played alot of BF2, HL2, BF1942, NFS, and RTW. All worked great on my old 15.7" CRT, but would they work on the widescreen lcd?
I finally decided on the Viewsonic VG2030WM, which is a 20.1" wide screen lcd. I needed to make sure the system would be able to churn out good game play at the very best of 1680x1050. So I went with cross fire 1950 pro's, 2GB mem. and X2 5200+. Granted, with this much power I should be able to play current games at the highest resolution with most or all details on.
I put the system together and loaded up some of the previously listed games, and I found out that not all will run at the monitor's native resolution. The good news is, is that they still worked great and looked good even with the games limited choice of resolution. I also got Guild Wars which does work at the monitor's native resolution, and that looks spectacular! I've recently picked up BF2142, which doesn't work at the monitor's native resolution, but still looks great none the less.
I think that most newer lcd's are able to scale down better than a few years ago, so even though some games can't operate at the highest resolution for a given monitor, they still look good. Pixel response times are generally better, and specifically with my lcd monitor, I have not noticed ghosting at all.
I think that you'll be happy overall with a widescreen monitor, just make sure that if you get a larger panel with a higher resolution, your current system will be up to the task. Good Luck!