I am in the same boat and figured there is no harm is downloading it. The file is 175MB and if it doesn't work later on I lost nothing.
Hmmmm - according to the linked page:
for Photographers, by Photographers.
PhotoTools 2.5 Standard Edition is the fastest and easiest way to add a professional look to your photos in Photoshop. Built jointly by working professional photographers and the photographers at onOne Software, you get dozens of professional-grade photographic effects, all wrapped up in an easy-to-use Photoshop plug-in making this the fastest and easiest way to make your photos stand out from the crowd.
The key to PhotoTools 2.5 is its unique ability to provide full-screen previews of an image effect before you apply it. With PhotoTools 2.5, you can stack multiple effects on top of each other just like you would filters over a camera lens. You can then control the order of each effect and their strength for a truly unique look. You can even save your effect stacks for future use and share them with friends who have PhotoTools.
PhotoTools requires Photoshop CS2, CS3, CS4 or CS5.
You should be good to go if you have one of those versions.