Many webmasters are now considering migrating their websites to the Joomla CMS. There are many advantages to migration, however, that is another topic altogether. Depending on the current situation of a website, one needs to decide which is the best alternative - creating a new joomla template or converting an existing template to joomla. There are several factors that need to be taken into account to enable the new website to achieve maximum potential and also allow for future growth.

So you are thinking of converting a joomla template?

A new joomla template is usually intended to improve the look of the website. This is one of the main reasons why many webmasters want a new template. One of the easiest options is to get a ready made plain HTML template from an online templates seller and get it converted to a Joomla Template. Some of the advantages to getting a HTML template converted to Joomla are…

1. Save Money! Cost is reduced as HTML templates purchased are cheaper than to get a customized design. After the template purchase, all one needs to do is convert it to Joomla or get a proficient programmer to do the conversion.
2. Save time! Since the design work - which takes a lot of time - has already been done, this approach is generally favoured by those who want a quick redesign. Conversion to joomla is also quicker since the template design is usually in HTML format.
3. There are thousands of plain HTML templates available nowadays from several sources, free ones like OSWD, Open Source Templates, Open Web Design as well as commercial template sellers such as Template Monster, Templates Box and Boxed Art. All these account for a much higher number of templates than the number of ready made joomla templates one can buy from a template seller. More HTML templates = More choice. Thus getting a joomla template converted gives you a wider choice. Choice is a good thing.
4. When specifying a template for conversion, one has full control of how the end result is in terms of look and feel. This is sort of control can rarely be achieved when one buys a ready made joomla template. You are in a position to dictate the look and feel as well as the functionality at every stage of the development to ensure that the end result meets the required expectations. This is very important.
5. Stand out from the rest of the crowd. Buying an attractive template may save you time and money initally but in the end hundreds of thousands of websites out there are using the same template. With the same look and feel. So what separates your site from the rest of the pack?
6. Some webmasters convert an existing template or website design to a Joomla template to allow the website to be ported over to the Joomla CMS. If the website has a large audience that is already familiar with the site’s structure, layout and content navigation, it is recommended to keep intact the look and feel as well as navigation menu items. This is primarily done so that, returning visitors to the website do not have a difficult time locating the content and resources required. Also a website that has maintained a particular look tends to have enforced its own unique brand that that may have taken years to build and reinforce. Thus one should pay close attention to these factors when designing a template for an existing website with a significant user base… but remember any upgrade always opens up many options and room for improvement!
7. Why consider anything else? Joomla is an award winning cms with a flexible template presentation architecture. By having a template converted for Joomla you ensure you stay with the most cost effective, feature rich and up-to-date CMS available.

Source: http://www.mozami.net/blog/2006/08/7-reasons-for-joomla-template-conversionhtml