The Olympus XZ-1 should be a supported file. You should be able to import the raw file straight into PSP without using an intermediary program aside from Windows itself. Now, whether or not you can actually see the thumbnails as actual thumbnails is a different story. They may just all have the generic tiff icon or something similar. You may try downloading the Microsoft Camera Codec Pack at http://www.microsoft.com/download/en/de ... x?id=26829
(or just search Microsoft.com for Microsoft Camera Codec Pack), but your camera isn't listed. PSP won't generate thumbnails for raw files that I know of.
ASP may not be necessary, but it may be easier. I however just use the software that came with my camera. I just don't like the way ASP is laid out and the non-destructive editing seems like you're chasing your tail sometimes. But don't let my opinion stop you from downloading the free trial, there's nothing like trying something for yourself.