BTW>The next version of GIMP will support CMYK color spaces. Although if you care about color accuracy, I would expect that it would not be adequate.
In any case, I am holding out for hte Cocoa Version of GIMP. I have weaned myself from PhotoShop, the only thing that PhotoShop still does that I no-one else does as well (for web development) is selections for things like dropping background from images.
I have not tried this on GIMP 'cause the interface in the XDarwin version drive me up a wall. I have a mental block against menus not being on top of the screen.
For my needs, PhotoShop is too expensive. FireWorks does everything I need but the selection stuff.