Content Management System

Your best bet would be paying someone to convert your entire site in WP and you'll never have to worry about CMS again, or hire a freelancer programmer to integrate it into existing model, but I wouldn't know of any freeware that is capable of doing this for you.

I agree with zannix.. Better outsource the entire site. Hire someone. It will speed up your process and also saves a lot of headache for you..

try going to elancer and get one created

I fully agree with using WordPress. It is free and simple to use. If you can transfer the content, your cost would just be for the time it takes to customize a theme.

I would rebuild the site in Wordpress at morecontrol.com/2 or whatever. Once its ready to go, then move it to the main directory and you are good to go!

I also wouldn't bother paying to rebuild the theme, its not a very pleasant theme as is. Better get something new, you can find premium themes for like $30-70 bucks that will do the trick, maybe even a free one out there that will work for you if you want to spend the time digging.

I wouldn't necessarily go for WP but the general idea of converting your whole website to a CMS of your choice sounds like the most logical and efficient option. That's what I would do.

If you use WordPress, there is a way to import your content from your other site. You'll see the option on the left-hand side of your control panel.

With WordPress, you can also create a 'home page' that shows up every time someone visits your site. I think WordPress calls it a 'static page' and it sounds perfect for what you want to accomplish.

You should first consider the ups and downs of different CMS-s. In your case, there is nothing you can get for "free". It's not a simple 10-article WP site you have there, it's much more complicated, and I think Drupal or Joomla would be much more suited for it than WP.
Again, you'll get nothing for free. Someone has to take your HTML template, and make it into another CMS theme. That could be any--WP, Joomla, Drupal, Mambo etc. A relatively easy task that an online freelancer would do for $50-100, and a brick and mortar design firm for $500-700.

The tricky part is to convert the data so that all your URL aliases, links and other dependencies remain the same. This requires an experienced PHP programmer who has knowledge both in your current CMS, as well as the one you choose to convert it into. If he first has to explore the current system, it may take days of trial and error first--before he even can get to work--and his time is quite highly valued. So, I'd suggest you first talk to the people who made the existing site. Maybe they come up with a solution that is not that expensive. But be prepared to pay at least within the limits that you paid for the site initially. If they already have a solution it may not cost you more, and you are lucky. If it's a custom job to be done it may be much more.

I would strongly recommend Joomla.

I have years of experience with joomla and I can assure you it is awesome.
And if you need extra features you can always take a look at Joomla extensions directory.

Peace

Many thanks for the input and advice. I think I'll go down the Joomla route, create a small test website with a fresh design/theme and then integrate the site once everything is working alright. So far there is about 1450+ pages on the old site, so I'm getting the feeling this might take awhile connecting all the dotts correctly.