Since you are using a GF2 Mx card, I wouldn't really want to have a resolution much larger than 1024x768 while playing games and I would try to keep it close to 85hz to maintain a picture easy on the eyes. This depends on what the monitor will produce for refresh rates. If you are using a 17" monitor, I wouldn't get a monitor that will do more than 1280x1024 cause at that size your eyes will be hating you. For a 19" monitor, I wouldn't get any with a higher res than 1600x1200 (and would probably still play games in 1024x768).
Now your 2d applications can be ran to the max size that you want and not really worry too much. I have a 19" monitor and I run my 3d games at 1024x768 and my 2d applications at 1280x1024 and that tends to work out good for me. I would say that's what the average resolution that most people would use. The only thing is that you will not be able to turn everything on with your GF2 MX card. You can have the higher resolution but I wouldn't turn all the "options" on without expecting a major penalty in games.