Resolution of Blu-ray movies on PC?

[Mibs]

I have a 22" monitor that has a native resolution of 1680x1050. As we all know in the HDTV world "full hd" or 1080p is a resolution of 1920x1080, meaning 1080 vertical lines. I recently bought an internal Pioneer BD-ROM and I've watched a couple blu-ray movies (Crank, National Treasure 2) and they look pretty sweet. I'm using the latest version of PowerDVD software. When PowerDVD opens the movie it is in a small window. So when I set it to fullscreen what resolution is it playing at? Since my monitor isn't big enough for 1080p is it playing at 720p and scaling down? Or is all that not important on a monitor and its just playing at 1050p? I've been searching the web and these forums trying to find some info and there are various opinions. Talking about monitors vs. HDTVs is a little different I think. I purchased this monitor about 6 months ago before I even considered "going blu" with my pc since it's mostly used for gaming. So should I be kicking myself for not getting a 24" or bigger to get the 1080p resolution? I have nothing else to compare to so I don't really know just how good the picture quality is. I guess I should get a blu-ray version of a dvd I already own and compare.