Creating a custom html module in Joomla 1.7 is usually an easy task.
But if the module should contain some Javascript you will probably the problem that the 'script' tag will be stripped out and the module does not work the way you want.
This behaviour depends on the editor you use in Joomla.
Depending on the template you use on your Joomla installation it may happen that the pagination (Next, Prev, 1,2) of the JDownloads component looks a little bit ugly.
In my case there were no spaces between the pagination links at the bottom of the page.