I got all the information I needed from here:
http://www.xbox-scene.com/I used info from that site to identify the best mod chip (at the time), and also a good guide on how to replace the hard drive and get started downloading and installing homebrew software (the hardest part is finding it...)
There are guides on softmods there too which look fairly straightforward, but I haven't actually used them since I decided to install a mod chip instead.
Edit-
My chipped XBox is inside my arcade cabinet, with UAE and MAME installed. One day I will finish the cabinet :-)
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moto