I have X61 with Vista, and I'm trying to install new 320G HD with XP, so I swapped HDD, put unit in dock, got <Press any key to boot from CD>, got windows file loading, and after that I have message <hard drive can not be found>, not sure is it because of bad dock.
This situation happanes with old HDD with Vista too. in both cases I see that valid HDD0 description posted in BIOS.
I did basic troubleshooting, and see that I can play/control DVD drive on dock from Vista setup no problem. No any security set in BIOS. I'm going to try to use USB CD later today.