On the web, what fonts should I use to create an equivalent experience cross-platform?
Here are some good up-to-date listings of the most-installed fonts for PC, Mac, and Linux:
Sans serif font sampler and survey results
Serif font sampler and survey results
Hope this helps your decision!
Most OS'es have support for Microsoft's Core Fonts For the Web. They all come bundled with OSX, and I'm reasonably sure they'll work (or have near-identical variants) on most any linux distro.