Preferring Gentium without limiting it to just the Greek characters has already been shown to diminish readability for other readers.
Could you tell me if the following process works on your system.
1. Create a new bookmark (I called mine 'Gentrify')
2. Paste the following text into the 'Location' field (no spaces):
Code: Select all
3. Save the bookmark,
4. Go to a page containing Greek characters; e.g. the fourth page of this thread.
5. Click the bookmark.
If this works, your Greek characters now display in Gentium. I suspect, though, Firefox 2.0 is too archaic, and you would need FF 3.0 and equivalent. Have you considered Xubuntu as a free alternative to Win98? The XFCE window manager is incredibly lightweight and will run on almost any old hardware. You can probably find it for $10-15 on a Linux magazine-and-DVD at your local newsagent.
For anyone else who wants to try this, you can replace "Gentium" in the above bookmark with whatever font you prefer. Just don't run it more than once on a page; the Greek text will keep increasing in size out of proportion to the English text.