It depends on the panel (man have I typed that word a lot today, as in JPanel) used...
If it is rated for 16ms, it shouldn't give you too much ghosting, but it can if it's a "cheap" (slow) panel, whereas 25ms "should" give you ghosting, but if it's a "good" panel it won't show.
The Samsung 173T is using a 25ms panel, but is hardly showing any ghosting.
The Di-fusion EA17 claims to be using a 14ms panel, but is really ghosting.
BTW: this is european models. Don't know if it's the same numbering/parts used in the US
So if you're going to buy an LCD screen, you'll have to do your homework if you want to play games on it.
From what I've read, it would seem that most LCD's over 17" is having a problem with ghosting, since the panels used just can't transition fast enough. But this should become less and less of a problem as the technology moves on (but how soon it will be ok, I have no idea).