If you are a big gamer, I would probably go for something closer to 8ms. Of course you can't always trust the spec'ed response time because they can be tested in different ways. I have the 2005FPW that is reported 12ms (16ms panel with overdrive maybe?). I've possibly caught small glimpses of ghosting but never noticed it to affect my gameplay. But I'm not a huge gamer. But if it truly is 16ms I think a fair number of people could detect ghosting, especially in fast-paced FPS games.
I don't personally like 19" LCDs much since they are 1280x1024. Just stepping up 1" gives you 1600x1200 and if you find the text small you can increase it a little bit.
20" widescreen is pretty much always 1680x1050. You actually lose overall space by going to widescreen, but for me it wasn't an issue at all. For games, the wider view is superb. For apps, I tend to side-by-side things more often than I need more height.