This depends alot on what you want out of the software.
I mainly use a PMac G5 and an older Mac-mini, but I also have 2 PC's on my segment.
On the Apple side, Toast Titanium gets much attention from me for general purpose authoring.
If it's something more specifically oriented to presentation then I use DVD Studio Pro which is part of Apples Final Cut Studio.
Final Cut Studio and DVD Studio are pretty pricey and if you don't have a specific need for it then it's very cost prohibitive.
For PC, the same company that makes Toast Titanium for the Mac makes a PC solution called Easy Media Creator.
I also use Nero though and can attest to it's versatility and reliability.
My point is that there are many options for general authoring, but if you need specific features for high end presentation your options are much more limited especially if cost is a big concern.
Are you sure your drive didn't come with ANY software?
That sounds odd. Did you buy it from a friend or something?