If you want to fax from a Windows 7 64-bit computer, and unless you are using a new laptop fitted with a compatible analogue modem, you will need to buy one.
The Windows 7 Compatibility Centre has a list of compatible modems, and a quick look at prices for aforementioned modems is a nasty business. The cheapest option is a USR 5637, a cute little white USB 56K modem which sells for cdn$60. Prices for others get really silly after that.
Some good news for Windows 7 32-bit users. The Intel 536ep analogue modem works, and I know this because I fax from a Windows 7 32-bit box which just happens to have a 536ep installed.
If I sent or received more than four faxes per annum, way more than four, I might just consider shelling out silly money for a 64-bit compatible modem. Intel, bless them, dumped support for modem drivers a while back and their website suggests going to the modem manufacturer website for support. Hey, Intel, I bought my no name 536ep modem for $2 four years ago from a computer breakers yard. The only name on it is YOURS..