Hi, samg914. I like to use Adobe PDF, but Nitro PDF is fine, too. Some people are used to online services. It is up to you. You just need to test it by yourself, to compare all advantages and disadvantages of these programs. Then, everything will be clear for you.
By law, a faxed signature is as good as an original because the fax machine creates a receipt.
The law has not yet addressed .pdf signatures, however, I can tell you lawyers use it everyday in practice. What we do is say in the document that an electronic signature (or sometimes more specificly a signed .pdf document) will be considered an original signature by the parties.
PDF's aside, a quick Google search produces tons of legal discussion and legislation related to electronic signatures. It it really true that the law hasn't addressed this issue? Certainly it's new technology and there isn't settled case law for 100 years going back, but there is a lot discussion about it and I'm pretty sure some legislation has been passed.
The fewer our wants, the nearer we resemble the gods. — Socrates