building a pda

I want to build a basic PDA.
It will use a:
text only LCD backlit with blue LEDs(adjustable brightness).
standard computer keyboard.
MAXIM microcontroller.
Ni-MH batteries.
a compactflash card(ASCII text).
Optional features I want:
ability to play MP3s.
support for word documents.
ability to run C.

Have fun! My knowledge of electronics is just enough to let me do a mod with lots of hand-holding. What I DO know is that there are some nice PDAs on the market that might be a lot easier to aquire than building your own...

I might be able to do something close....

2-4 line text display with normal LED backlights replaced with blue/white. Get one with a built-in controller for handling 'font' items.
Keyboard taken from a cheapo translator-device.
Dunno 'bout the controller- shouldn't need much (except for the mp3's)
NiMH, ok.
CF-Card (don't know enough about it)

Should be possible to make one with built-in ram, and a USB connection for transfer (code updates, battery-charging, .txt files, etc)

Unless you want to spend a LOT of free time, and likely a lot of l00t, it will be easier to find a commercial product. Now, if you're willing to take a compartment-clipboard and mod it with all this, THAT's possible. Might it be feasable to make a custom Linux distro that'll fit on eeprom for it? I don't know enough about the deep-end of this.

What microcontroller do MP3 players use?

The Psion 5 series is CLOSE to what you want.

Doesn't Run C, but it does run OPL