Wow, that's pretty good. I've only ever used the free version.

Nice animation.
The newest version (Howler-9), is pretty amazing software. I especially love the animated orbicles brush.
I really wish GIMP had something like this available.

I bought PD Particles when they offered it on special. I love the brushes. I found it works under Wine on Linux . But it doesn’t work well as a gimp brush maker as it renders an aura or halo in strange colours when cut from a png on a white background. It has a psd option that doesn’t work with Gimp or CS2. I haven't yet tried targa as I’m not sure it supports transparency. I have the free version of PD. I will have to see if it works under Wine and if its brushes do the same.

Yep, .tga was the way to go. No funny colours and selection is easier.