Are those TFTs ? The larger TFTs are still not as fast as smaller ones such as 17" TFTs. 19 TFTs are borderline for gaming if you don't intend to spend more then $400 for a low response time TFT, but 20" & above are still way to slow to play FPS games for example.
If you play RTS games or games such as WoW, it won't be as evident, you might actualy not notice a thing but for fast paced games, it won't be acceptable (especialy considering the price these go for).