Fraps - is a good screenshot capturer while in game and it has its own folder where images are stored to view after playing -even a mini vid too. Uses a tiny amount of resources, but it has frame rate measurer on screen while u play.
http://www.download.com/Fraps/3000-2121_4-10441285.htmlIf you use irfanview; First right click any jpg image on your comp, then select irfanview from the 'open with' tool choices- but remember to click a tick in the box at the bottom of the choices to 'always use' irfanview to open your jpgs [if u have xp]