I always like the idea of validated code. You need to start with a declaration though, what type of code you're writing in, ie html 4.0, 4.1, xhtml, whatever. Make sure you close all your tags too, even the simple p or img tags. Not only is that a step in validating, it'll also make it easy to switch over to CSS.
Which bring us to point number 2. Center or font tags aren't terrible, but they're not the best you can do. Your page already has a very logical setup and is nicely grouped. All the pages follow the same basic structure. CSS should cut down on the size of the pages dramatically, which is always good. It's worth learning anyway, and makes pages a lot more flexible.
A few little things too, like always declare more than one font, just in case the first one isn't supported. Placing the logos to the left of the description instead of above will cut down on the height of the page, and you might even want to use links within the pages to avoid scrolling. You already have the names of all the programs at the top of the category, so why not use 'em.