I was only contemplating a new one because of the size screen; I do a lot of work on the computer.
In that case, you would probably find a widescreen monitor to be quite an improvement in working with your computer. A 19" widescreen or 22" widescreen would give you a lot more screen space to work with and perhaps to display two application windows side by side.
Dual monitors is another option I'm sure you'd like very much. To run dual monitors, your video card must support two monitors. I run two monitors off an eVGA GeForce FX 5500 (256MB of memory) card; it has both a VGA port and a DVI port. I have an 17" CRT and a 19" LCD monitor connected to it.
I don't know what the memory is on my current video card; does the number 128 mean anything?
Per
http://ati.amd.com/products/rage128pro/aiw128pro/specs.html, I believe it only has 32MB of memory. One way to verify the amount of memory is to run dxdiag. To do this, click on Start, Run, and type dxdiag in the box. Wait for this utility to execute and then select the Display part of it's report to see some details on your video card.