If you have a h140, you must try Rockbox! It's superior to the original firmware in almost every way. There are install instructions here:
http://www.rockbox.org/twiki/bin/vie.../IriverInstall
Basically, you patch the original firmware to include a bootloader thats loads the rockbox software from disk. The bonus is that the original firmware remains and you can run it at any time.
The menus themselves are rather spartan, only text, but they're easy to use once you've gotten used to them.
Features:
-Support for many formats: mp1/2/3, ogg vorbis, mpc, ac3, aac (still not quite done), wav, flac, alac, wavpack, and shorten.
-Supports gapless playback, cross fade, replaygain.
-Powerful on-the-fly playlists.
-Many, many customizable options, including the "while playing screen". (
http://www.rockbox.org/twiki/bin/view/Main/WpsGallery)
-More features for recording. (still being worked on)
-Many plugins and games. (including a gameboy emulator)
-And much more...
The only things you might miss are:
-Remote support is only partially done, but should be done soon.
-No wma support.
And if you do miss these, you can always boot back into the original firmware.
I've been using rockbox on my h140 since June and have had no problems with it at all.