The 9450XE is fitted with a standard Award BIOS that has been slightly customised by Wyse. The BIOS is entered by hitting the DEL key during the power-up sequence. If you find the BIOS is password protected (mine was) the default password is Fireport.
The BIOS boot options are:
Of course, if you have no interest in the 'WINTERM' aspect of the device, there is no reason why you can't dump this BIOS and install the standard VIA BIOS available from the VIA website.
I have had no joy trying to boot pen drives using the USB-HDD option. However this article describes how you can set up a pen drive that will boot using the USB-ZIP option.
The 9450XE runs Windows XP embedded.
The BIOS on this VIA motherboard only supports hard disks up to 137GB (when running in LBA mode). This has been confirmed by VIA's support channel whose comment (June 2011) in response to an enquiry about this was essentially:
"The maximum disk size is 137GB. The board is ancient and no longer supported. You should buy something new."