I was able to get my DVD key by installing the JTAG connection to my Xenon and then running Xell so now I have my CPU key. I dont plan to use this 360 for homebrew and was wondering if after I update it I might be able to change the region from US to EU and JAP and such still? is this affected by the recent changes from M$?

you should still be able to do it
the m$ update doesnt block reading or writing the nand, that is still possible, so i dont see why not

NO, if you update you are screwed. even the CPU key will not protect you. the jtag hack will not work anymore if you update to the newer dashboards (after august (8xxx))

DONT update

Let me tell you from personal experience, if you upgrade to the dashboard released august 09 (or newer), you WILL NOT be able to modify the NAND to change the dvd region, or use the xell hack further.

I'm sure if you kept the CPU key you can still change the region and flash it back regardless of updating. You just cant use Xell anymore.

In theory you can still change the region, yes, but there appear to be problems changing the region on recent dashboards; it may be that you need to change multiple places, not just the single configuration value that works on older kernels... not sure if anyone has figured out the details just yet.