Fonts are machine dependent. Outside of the basic ones, you cannot depend on a machine having the font you want. You need to have 3-4 roughly equivalent fonts, that you list for any given font in your css. List them most prefered to least (left to right) for your font-family. Machines will also display even some common fonts slightly differently.
Also remember that while you will often pull your site up side by side in both IE and Firefox, on Mac and Linux, your users almost never will. It doesn't need to look the same in all browsers, it just needs to look good in all browsers.
You're basically asking for rich functionality without any of the rich functionality platforms (javascript, flash, etc.)
I realize this doesn't answer your question, I'm trying to step it back a bit. Image rollover without any of the above platforms is hard, but possible. But it will probably require that you give up on the site being exactly the same in all browsers and just go for "good"