One question about PHP Nuke. Does it support friendly URL’s?
If there is a way of using that, do not hesitate. You will be far better indexed by search engines.
In the past I had a few sites with PHP Nuke and at that time no one cares about these friendly URL’s, but now the best content management systems support this, at least as an extension, and it is important.
If you cannot put this feature to work, I would consider using other script like mambo or post nuke.