This is simple and I must begin with the most famous mantra around: To each his own. But I will try to recommend some programs although you should let yourself try several until you find something that ... well, suits you.
Video (of almost any kind...files, DVDs, etc): Mplayer (Pre4...latest I think)
Receiving mail: Thunderbird (Mozilla)
Fun little something: MrPostman (this allows you to retrieve your hotmail or yahoo mail...from your free
accounts!! I love that
So it will act as the go between for Thunderbird and hotmail/yahoo. You never will
run out of space again as each email is downloaded to your computer. )
Webbrowser: Firefox (Mozilla) Get Flash blocking
Digital Photos (usb downloading): Gphoto2
Editing Photos: hmm... Gimp2 ? Though that might be overkill. I do use it.
What else (gotta love the "Thinking to myself" commentary)
Fluxbox (window manager...not a full environment like Gnome/KDE, which may mean its too difficult, but if you
can handle the command line, then this should be no problem. And your start up time is reduced!)
And some day in the future after you are comfortable with your system...say MythTV. Your very own TV time shifter. Yummy.