A LOI is typically used as a "starting place" for negotiations on a property. Generally a LOI will be followed up by a formal Purchase Agreement after the terms are settled on. This may or may not be the case in your area, but is a good use of the two documents.
These are but a few of the possible issues that you need to keep in mind when drafting up a business letter of intent. And, although it can be an expensive exercise, you really should consult your lawyer before you commence.