Word 97, with different locales depending on which language I might use.
I checked the link, but the problem isn't creating Greek text (both fonts and symbol work fine), it's solely copying the text to fora which doesn't work (and the other way around). Copying from forum to forum seems to work well enough.
Eλληνικά μέ πολυτονικούς χαρακτῆρες looks fine to me
ellenika me polutonikouv karakthrev is what I get when copying it from word. It just 'fixes' Greek back to standardkeys where v is ς and h is ῆ .