Listed here are programs that I use and like better than the alternatives. I think these are worth a look.

Vista tn3270 is a 3270 emulator written by an MVS systems programmer. I like it a lot better than any of the others that I've used, including expensive commercial products.

Tera Term Pro is a telnet (vt100) command without the aggravation in the one that comes with WinDoze. This one's free.