Well WinFax is regarded as an excellent program with many features, but it's not free.
Microsoft includes a simple fax program--maybe that will meet your needs?
There are bound to be others. Why not do a search at TuCows or shareware.com?
If the internet service you refer to is Efax.com I can vouch for the fact that it is indeed very good. They're always trying to get you to upgrade to the Plus (paid) service, but it's not that big of a deal. It's cool, when they receive a fax for you, it's immediately e-mailed.
Hope that helps.
l2c