OkAy.....Simple question, and with my luck...no simple answer. Can I replace my stock hard drive with a western digital 120g hard drive? and, Can I add the 120g as a 2nd drive in an external case, or do i have to use the extnder thing ive seen floating around on the web?
yes you can replace your stock hd with a 120gig hd, but your xbox must be modded. you can have 2 hd's without the extender, but you will need to make a switch, and get a new ide cable...you can't run both hd's at the same time that is why you need a switch...the switch just regulates which hd will get the power. also it is very difficult to get 2 hd's into the stock xbox case...you will have to do some serious case modding for them to fit in there...that is the only benefit for getting the xtender...or you can do what i did and simply mount a 2.5"(laptop hd) under the dvd rom...just need a ide adapter for the laptop drive and it works excellent.
if you have a modchip, just put the hd in and use slayer's to format the drive and install everything for you...if you don't have slayers you will need to create a evox boot disc, boot up with the boot disc then you should be able to ftp over a dashboard...most hd's work fine but not all hd's will work...yours should work fine.
Actually all ATA hard drives will work in the xbox; but not all support hardware locking (a feature that matches the motherboard serial to the drive). You can find a somewhat reliable compatability list at http://xboxdrives.x-pec.com/.