Believe it or not, I just made the DVI switch myself. I've had a new 18.1" Sony LCD for a few weeks. Since I initially purchased it, I've used a GeForce 2 MX to drive it. I thought it had awesome 2D from the get go, and I was very pleased with the initial performance at 1280x1024 native resolution.
Two days ago I installed a Radeon 7500, basically to experience the DVI improvement. Most agree that the 7500 is an excellent 2D card, if not the ultimate 3D card. I game very little anyway.
When I'm being honest with myself, I'll confess that the improvement isn't day-and-nite. Yes text/graphics are ever so slightly crisper. If there is an improvement in the colors, I haven't noticed it much in daily use - the colors were fabulous in analog.
So manage your expectations for DVI, and upgrade when the funds are available. It is an incremental improvement, but not a new wheel.