I haven't visited that site in a long time. (And it actually doesn't even seem to be loading for me right now). If you can't .abr format, then you either have to get in touch with the maker of the resource or unfortunately, just forget about it. There were a lot of times I couldn't use something because it was made for Photoshop 7 and I only have 6.

Try searching for Image Packs (those are just JPEGs, so you can use them with any program).

Other than that, I can't give you any further advice. Sorry! :(