After spending many hours recompiling kernels with different modules enabled, disabled and compiled in, what I have come to find is that the following criteria MUST be met:

* All i2c drivers except the following must be compiled as modules (the following list may be compiled as modules or compiled in). However, if you are using rivafb, the following list must be compiled into the kernel (modules wont work!):

i2c-proc
i2c-core
i2c-dev
i2c-xbox
extsmi

* The NVNET driver must be compiled as a module
* SCSI, IDE-SCSI emulation, SCSI-Generic, SCSI-Drive must be compiled into the kernel to allow USB HDDs to function.
* SCSI-Cdrom must be compiled as a module to allow USB CD drives to function.
* Xbox support (Under processor menu) must be compiled in - duh
* Xbox partition support and fatx must be compiled in if you want access to the Xbox partitions
* PCBIOS partition support must be compiled in if you are using linux on the whole hard drive. If this is the case then Xbox partition support is not needed.

The rest is pretty much down to you. I hope this helps with anyone wishing to compile their own kernels!