Too bad i can't hold you to that bet. I started using Irfanview when it first came out. It was about the only program I could find that would generate a decent favicon Icon. I used it until last September when I switched to Linux.
Besides windows picture viewer, when I had windows, my default viewer was the one that comes with XaraX. I also had photoshop in my pc, but I rarely used it since I prefer to design is vector format rather than rastor. As for the XARAX viewer, it did a great job of allowing me to resize photos either up or down (as long as they were uploaded in a decent DPI).
However, the XARA distro for linux is crap in comparison to the program in Windows so now I use Inkscape and Gimp for Design but prefer to use the Linux image viewer for simple viewing of photos.
BTW... I have also used Google's Picassa. I just plain out don't like it.