I have heard there are ways to remove image retention, however I don't know what these are. Google would be your friend there.
If you do end up upgrading, you don't have a massive amount of choice in terms of 1920 x 1200 monitors. Most these days are IPS panel as far as I'm aware, which isn't a bad thing. For general use, I've heard good things about both the Dell U2410 and the HP ZR24w. I even looked at the HP myself.
The HP has a standard gamut panel so will be more suitable for games and such, but not as good as the Dell for photo and colour critical work (someone correct me if this isn't strictly true

). In terms of warranty, I've heard good things about both Dell and HP. Dell offer a zero bright pixel next day swap warranty. Pretty sure it's the same thing with HP.