I was listening to the Xero current folder yesterday and noticed a few things:
"SLIP_1" and "SLIP_2", they're not present (from what I heard) in the version with Chester; perhaps it's the 1998 version with Mark on vocals, which they said was a bit faster and had a similar arrangement.
"OUTSTEP!", Could this be the end of the Xero version of Step Up? The sample repeats "step up ste- step up.", If you look closely, it has a tape-stop effect on the end. It reminds me of "(And you do it like this)" from the Hybrid Theory EP version.
"CHAZAAAH" Maybe the vocals from Turn to Grey?
There are also samples of the riff from Carousel, possibly the Xero version of Carousel from 1998 with Mark, or the first version recorded with Chester from April/May 1999