I know that if you open an illustrator file in Photoshop it asks you what size and resolution you want to rasterize it as. You wouldn't nessicarilly want to take a psd file into illustrator unless your tring to create a vector shape from your raster image. Otherwise you mainly want to work only with shapes in illustrator. It's not designed to edit pixle based images. If you got more questions hit me on the PM dogg.