Please help with monitor problem

[Irieguy]

I just got a Viewsonic 19" monitor with 2048 x1536 max resolution. But when I got it home, I could only go to 1600x1200 resolution. The computer dude told me that I need a new graphic card. Fine. I bought that and installed it and I still can't get 2048 x 1536. I followed all the instructions in the advanced monitor display settings and I still can't get it to work.

Can anyone help me?

Irieguy