Microsoft has removed HyperTerminal from Windows Vista, if you need to connect to a Cisco router through a local COM port, you can get HyperTerminal from Hilgraeve, the company that Microsoft licensed the application through.

You could also use the old XP Hyper terminal. Just extract two files hypertrm.dll and hypertrm.exe. You can put them anywhere on the disk, no installation required. Of course, for that you need to have XP to extract files from.

Besides, puTTY and SecureCRT are great too! I would prefer puTTY as it is FREE! :-p
PuTTY can now connect to local serial ports as well as making network connections!!!

Hilgraeve HyperTerminal for Personal Use
puTTY