upgrading old dell 19", going to 20-22"

So i'm currently using a really old dell 19" lcd monitor, 1280x1024 max res, and its lookin a little blurry and small and bulky. So I've decided that i'm going to start upgrading it. I was looking at a viewsonic VA2226W 21.6" lcd (22") that runs a native res of 1680x1050. But there are also some 20" monitors that look pretty good too. Mainly, I just want a monitor thats 20-22" and has more pixels per square inch than this one. I dont want an HD super high res monitor, so I'll say that 1680x1050 is max for resolution. Too high above that and I will suffer too much performance loss. Current graphics card is HD 4870 512mb, but am getting a HD 4890 toxic soon. $250 is my price limit.