most people can't notice the difference between panel types. you'll mostly likely be overwhelmed with the size of the monitor itself to really care. i'm came from a 19" TN panel samsung lcd to my dell 24" PVA panel lcd and when i first got it, i was overwhelmed by its size and how bright it was compared to old my 19" lcd. i had to turn it down to 45 just so i could look at the screen without straining my eyes.
usually 22" and below use 1680x1050, while 24" and up use 1920x1200 before going into 30" territory. when it comes to desktop space, 1920x1200 obviously has more. i've used a 1680x1050 20" before and while you can do 2 things side by side, its just a bit more difficult compared to a 1920x1200 screen.
gaming-wise, you going to need a faster video card with at least 512MB of video memory to power a 24", ie. GTX/Ultra class cards. for 22" screens, GTS320/640 should be enough. since you have a 8800GT, you should do fine even with a 24".