First off, let me warn you that my Windows knowledge is limited, since I don't use it. With that out of the way...
As you may know, Vista does not allow any software to run unless it's approved by Microsoft. Claire specifically instructs you to use version 6.5.8, which is quite old now, so no, it's not supported by Vista. You probably want to install the
latest version. I doubt the warnings at the end of
Claire's article still apply. They're at version 9 now, and version 6 should of course be considered crippled as well, since it won't run on Vista at all.

The separate freeware version has been discontinued and integrated with the commercial version. You now get one month of free trial, after which it will revert to
crippled freeware mode, which you're allowed to use indefinitely. Or you can convert it to Freeware immediately.
Tutorial here.
I'm not sure if I should mention this, but version 6 was the last International freeware version, which was independent from the PGP company. There have been rumors that the newer versions contain a backdoor. Then again, if your threat model goes this far, Windows should be considered backdoored as well. So either you avoid Windows, or this argument is null.
As for protecting your e-mail address from those nosey bastards:
https://spamgourmet.com/https://www.temporaryinbox.com/http://www.mailexpire.com/The rest of the form can be filled out with fake info, I think. Javascript required.