i dont own an xbox, but i have a few friends that are heavy into it.
what i know is:
1. you will void your warranty. but for $150 bucks, you cares?
2. you will need a modchip. choose this carefully, because it has to be compatible with your generation of xbox. (at least this was true about 6 months ago, not sure if anything has changed)
3. Most good modchips require soldering onto the mainboard. You can attempt it yourself if your confident and have the tools, or find someone to do it.
4. You will then need software. I think you need a different bios, and probably something else. All software is available online, thru bittorrent sites, or IRC. check around.
5. Best way to save games to the hdd is probably to rip them or download them on your computer, and then send them across a lan to your xbox. This will of course require some screwing around to get the xbox to talk to your computer. firewall settings play a part of you are running winxp.
I know these arent the specifics you were looking for, but there plenty of sites out there to get you started. This is no easy process, and it requires patience. Heres some sites that should help you out:
http://www.tweaktown.com/document.ph...rticle&dId=602
http://www.matrixmodchip.com/
http://www.xbox-modchips.com/xbox-mods.htm