I think that replacing the hard drive on an ipod is possible, though the difficulty will be in acquiring the higher capacity drive for upgrading an smaller capacity ipod 20 or even 40 gigabytes.
Opening the unit:
There are abundant instructions on the internet for cracking open an ipod. Many people appear to have been successful at doing so in order to replace the ipod's battery. The plastic front of the device appears to be press-fit into the stainless steel back, and may simply be pried off. I saw an article somewhere stating that guitar picks are a good way to get the case open without damaging it.
The hard drive:
The 1.8" ipod hard drive appears to be manufactured by toshiba, which utilizes them in PC card based hard drives, but largely appears to market them to makers of portable mp3 players. Hard drives from older generation ipods appear to be interchangable with those found in newer generation ipods:
http://www.anandtech.com/audio/showdoc.html?i=1575&p=5
It is not known at this time whether or not it is possible to obtain one of these drives and insert it into an ipod, as the ipod may use a special connector for its hard drive.
http://www.techtv.com/screensavers/a...472745,00.html
At this time, it appears that the toshiba drives come in one platter and two platter versions. The largest single platter version as of November, 2003 is the 20gb drive found in the current generation G3 ipods.
http://www.findarticles.com/cf_dls/m.../article.jhtml
Information on the drives may be found directly from Toshiba:
http://www.sdd.toshiba.com
A list of suppliers may also be found on the toshiba site. I do not know if it is possible to obtain a drive through one of these distributors.
Software:
This should be the easy part, as Apple provides a hard drive formatting utility for the ipod. This software formats the drive and to install all the requisite drivers etc.
This is the desciption of the software's function from ipodlounge:
The update command downloads new software to an iPod. The update command may be disabled if the iPod does not need to be updated because it already has up-to-date software. The restore command returns an iPod to "factory fresh" condition. It erases and reformats the iPod before downloading new software. WARNING: The restore command erases all of the music and other data currently on the iPod.
Apple ipod software 2.1 is available here:
http://www.apple.com/ipod/download/
Please note that this version of the software is only compatable with G3 ipods. I believe version 1.3 is the version compatable with the older models. A link to this software may be found at:
http://www.ipodlounge.com/downloads_windows.php
Anyone who wants to upgrade an older 5gb ipod or a fix an ipod with a broken hard disk want to give this a shot?