Oh, but for simply viewing pictures, (sometines resizing them, if I wont add a border or cut it or anything, I use IrfanView, extremely lightweight, good, and made by a bosnian guy
Oh, and if you need to resize multiple images at once, MIR .net is a great free choice.
I use it for resizing the pictures from my phone. I always use the highest resolution and best quality when making photos, so they tend to take up a lot of space. I transfer them to my computer and resize them to 200 x 150 and transfer them back to the phone. That way each picture takes up 5-10 kb instead of 150.