I'm making a scrapbook and I need to print some photos as 2.5"×2.5" but have no idea how. I currently use Picasa and can print 6×4s and 2×2s but not what I need. Can anyone suggest a free program or simple way I can do this?

Also, in photo shops where they have the machines where you select and choose to print your photos, can they print in 2.5×2.5" format?