The chop saw and the cordless drill are indispensable site tools. Many builders who purchased them only after years of indecision now wonder how they ever got along without them. In the office, the fax machine — and now the fax/modem — fall into the same category. Users familiar with fax machines know how valuable it is to have an invoice or brochure faxed to them in little more than the time it takes to dial a phone number. The fax/modem, which works in conjunction with a computer, adds a new dimension to office management by allowing you to create, store, manipulate, send, and receive documents electronically — without printouts, copies, or faded and curled images. What Is a Fax /Modem? A