I use HTML::Template quite a lot and I find it very easy to use and very effective. The advantage of using such a system is that you don't need to change the script every time you make changes to the web page.

However if you are the only person developing scripts/web pages then as far as I know there is no official ban from putting HTML into your script (though previous similar conversations on this site might give that impression).

If you haven't tried HTML::Template, though I suggest you practice with it as it really is a very good, flexible option. The Author has put up a web page to explain it - I suggest you take a look at that before you get started.

Update: Altered links.