Installing ESXi to usb flash drive issue

First off this is for my home setup.

I recently bought a DL360 G5 off e-bay.

I ran the firmware update DVD

then I inserted the following flash drive into the internal USB port

http://www.amazon.com/gp/product/B005FYNSZA/ref=oh_details_o01_s00_i00?ie=UTF8&psc=1

And then ran the HP customized esxi installer

http://h18004.www1.hp.com/products/servers/software/vmware/esxi-image.html

after it ran to completion and said to remove the disk I did, but on reboot I get "invalid system disk"

any ideas?