OMG! FINALLY IT WORKS!
Here is what was wrong: for some reason the BIOS revision on my Foxconn nT330i was buggy... in the Wakeup Configuration page (which becomes available when you disable Deep Sleep mode), my BIOS gave me no options at all...
This was odd, but I figured that because it's a pretty cheap entry level thing they keep things simple... I was wrong. This is a bug in the BIOS.
For anyone else with an nT330i who has the same issue:
Download the 1st May BIOS revision from here:
Foxconn Support for nT330i
Before you flash your BIOS (I'm not going to explain that, but you'll obviously need a USB key that boots into DOS, there's a good guide
here), you need to edit the DOSFLASH.BAT batch file. This is because if, like me, your BIOS is corrupted, it won't let you flash the BIOS without the /C switch, and DOS crashes when you try and add it in, so add the switch at the end of the batch file command line before moving to your Foxconn and booting up...
After that's done, there's another error on system restart. This advises that there's a checksum error, and gives option F1 to enter setup and F2 to load default config. You want to
load default config (F2), otherwise when you try to enter your own the Wakeup Configuration page is still blank.
Now that you've done this, the BIOS is fully functional, you can go into the relevant page (as per page 13 of
this PDF from Viewsonic's website) and enable wakeup from USB...
Now it's all fully functional... you have no idea (actually, you probably HAVE given you're reading these posts) how satisfying it was to sit on the sofa, hit 'Media Centre' on my Harmony One remote control, and have everything fire up
Cheers for all the help on the forum... tell you what if I'd had to type 'echo USB0 > /proc/acpi/wakeup' into a bloody prompt one more time I think my brain would have exploded!!!
Luke