[quote name='SteveMcQ']I'm guessing it has its own software to transfer files. How is that? Is it serviceable, or do I have to look for 3rd party stuff?[/quote]
It does, but it's not necessary if you're on XP. You can simply drag/drop files onto it. Same with video (if the format is not supported it will ask if you'd like to convert and use its built in conversion tool.) The player supports a shit ton of video formats if you like to watch stuff on it. The screen is much sharper than the iPods, which looks really washed out in comparison.
The battery life is good, too. It's not amazing, but I've never ran out.
I'd go with the M over the W, for the better button layout and smaller size. The extra screenspace on the W really isn't that much if you're watching anything in 4:3, as you will get black bars. The one thing the W does have going for the it, though, is the replacable battery pack.