BTW if you're that convinced having the same font set on every
platform is a must for web rendering, I suggest you ask the Mozilla
Foundation to bless an official FLOSS font set for Firefox, distribute
it with Firefox itself and set Firefox defaults to use this font set
Depending on proprietary fonts other platforms are hard-pressed to
replicate is contrary to MoFo official "free web" objectives anyway.
And MoFo has the resources either to coopt existing FLOSS fonts or
contract a foundry to create a new set. If you can convince it to care
about the problem in the first place, that is.