first of all, if you have a 1.6 xbox you NEED to get a 1.6 EEPROM otherwise you are willing to destroy your xbox... if you have a 1.0 - 1.5 then 99% you can use 1.0 -1.5 EEPROM but read before doing so...
second of all stop using configmagic and other programs since we have X3 CL!!! you can change your EEPROM from there (just upload the new one in the Admin DIR while being in X3CL!)... and the funny thing is that all these people asking for a new bios cause they want to use the new functions are not aware of the existing ones since they suggest using Config Magic for changing EEPROMS....
if you change your EEPROM and IN THE SAME TIME change your HDD you will be safe accessing XBOX LIVE! again without any problems...