Irfanview - that's a very good one, and also install its RIOT plugin, which lets you easily control output file size. Take the time to play with it, learn to crop and resize images, as well as a few of its image adjustments to "pop" things, improve brightness, contrast, etc.
It's really an awesome free program and has a minimal amount of "astonishment" of graphics editor software with similar horsepower.
I haven't completely explored how well Windows 7 plays videos, I suspect it is pretty good. Windows Media Player is a pretty good program, but I also recommend another freebie program named Media Player Classic; it also seems well behaved and handles quite a few video formats.
I have Windows 7 on my laptop, which I seem to only use in the hospital (because I despise "chiclet" type keyboards on laptops) and
I did like some of its features. Once I disposed of the fruity, "clippy" (Vista?) style interface, it slimmed down to work similar to trusty old Windows XP Pro; more manly non-Tweeting, non-facebook computing people like myself actually use it with reduced torquing of the jaw.
Good luck! ;->
L.
"Time is a great teacher, but unfortunately it kills all its pupils." -Hector Berlioz