Even older browsers that support SSL often lack up-to-date root certificates, which prevents them from establishing trust with modern SSL/TLS certificates.
Fairly recently I attempted to get an (FPGA-emulated) Amiga, a G4 Power Macintosh running System 9.2, and a Win2000sp4 Virtual Machine online (just for very select downloads of trusted applications, not for actual browsing). It came as a huge surprise to find that the Win2K VM was the biggest problem of the three.
