Deciding upon what kind of website a company/person or organisation is going to have can be a very difficult task.

The main point to consider is "what is the purpose of the site". Why have you chosen to have a website and what do you hope the website will achieve.
Many smaller websites are purely created because their market dictates that they have to. With many, if not all of your competitors having a website, it is important that you at the very least match their efforts. (Though HCOMS are a website design company you would expect us to say that!) The term brochure website generally refers to the fact the content of the site is fairly static and the look resembles that of a brochure.
A CMS website is generally used for websites that require frequent updates or the site will need to handle a large amount of data. When a website uses a CMS to control certain areas of the site such as the news and events area it means that the person running the website does not require any specific website design skills (For example HTML knowledge) A CMS is ideal for a site that will store a large amount of similar data. For example a website for a car motor dealer that has 250 products.
The car dealer does not wish to sell on-line however they wish to advertise thier products on line. There could be two solutions for the car dealer, either a brochure website could be built with a new HTML page for each car, or a CMS controlled site could be used. The information on the cars would be stored within a database accessible through an administration area. The car details would then be pulled from the database and combined with the product "template" page. It would be considerably more efficient to implement a CMS powered website to handle the car dealer website than to create a new page for each product.
The initial cost for the brochure website may appear cheaper, however if you have no real website skills then the website designer would have to create/edit a page for each new card or change to that car. It would actual be in the financial interest of the website designer to push you down the brochure route because it could result in a large number of updates. HCOMS would strongly suggest a CMS system for the car dealer scenario. Though the initial cost may be more than a brochure website the cost over all will be considerably less.

When do you need E-Commerce?

E-Commerce can be a relatively cheap method of selling products to potentially every user on the web. However not every user is going to be viewing your site let alone purchasing from you.
Advertising and brand awareness are just as important selling online than the original "bricks and mortar" type shops.
It is important as well to remember that some products are "touchy feely", products which need to be viewed and touched before a shopper will purchase. The Mail order industry suffers from the same problems and overcome this by added benefits. For example the ability to spread payment over a period of months. Generally speaking online shops work because there are cheaper and more convenient than shops in the city. An e-commerce site is ideal for those products which lend themselves well to a distance shopper and when you can add additional benefits.