I'm glad to see other 500 series fans on this forum. I have a 520, 520c, 540c, and a 540c with PPC processor upgrade. I just need a 540 and a 550 to complete the collection (I doubt I will ever get the 550...it's a ghost). I'm trying to get spare hard drives as they are hard to come by. I just bought a CF adapter to see how it runs. Another one of my dreams is to get the type 3 cage but that is also tough to find.