Here is a free brush pack. No restrictions. Free for personal or commercial use.
http://jeffretta.deviantart.com/art/Ultimate-Space-Brush-Pack-Part-1-323841249
How to get rid of the transparent background in CS Photoshop 5.5
1) Go up to the ‘Window’ menu in the Menu Bar
2) Choose ‘Application Frame’ down near the bottom of the list of options.
3) Voila.