Sorry, to clarify: mIRC no longer works under 95/98, but it does work on other versions than Win7. As said, 98 is too old to support anymore. There are new features in Windows (like Unicode, IPv6, the very features this beta targets) that make it difficult to maintain backwards compatibility and slow the progress of mIRC.

You can always continue to use 6.35. Again, if you're on a pre-XP version of Windows, you won't benefit from many features in the 7.0 beta anyway.