|DVI & HDMI send the exact same digital graphics signal. HDMI is just DVI + audio in a single cable. As long as the new monitor supports DVI, you're good to go.|
"Do you have a suggestion for a good replacement graphics card"
The Radeon HD 4650 is a decent performer, but it's becoming a bit dated. If you prefer ATI/AMD, you'd probably be better off with something from the HD 5000 or HD 6000 series. What's the primary use of your system? How much would you be willing to spend on a card?