I use Lumiere Video Studio to edit. I make graphics FOR the edit (eg, introduction screens) in Macromedia Fireworks.
To get screen caps, specialist software is available. It's pretty expensive though, considering the alternative...
- pause the movie
- make it full screen (in Windows Media Player)
- press print screen
- paste to MSPaint (I don't know why, but pasting to any other program doesn't work)
- save as a 24bit bitmap file
- import to Paint Shop Pro
- Resize and crop as required
Of course, it gets a little tedious after a while making caps like that... but it works
That works for mpegs, avis, movs, asfs, reals, whatever.