Ok, so not quite seamless.
The install went smoothly enough.
Mounted iso using Microsoft's XP utility, then copied it onto a fast SD HC card. Ran setup from there.
When this finished I found a nasty glitch. There's something wrong with the BIOS and the display. The Windows 7 starting graphic is too low - as if it thinks the 600 high screen is 768 instead. Then it goes black.
If I shut the lid - so it goes into standby, then press the power to wake it everything is fine again.
Everything else installed fine - I needed the Super Hybrid Engine Utility to get the ACPI drivers working, and I needed that to get the function keys working. Otherwise fine.
The one problem is this video bug on startup. Bloody annoying.
Much digging around has lead me to a BIOS hack. Messing up stuff on disk is always fixable, but there's no way that I'm risking a hacked BIOS - far too high a risk of bricking the machine.
I think this bug is something to do with an updated BIOS - there appears to be a newer version on the ftp site, but it isn't on the official download page - are they beta versions?
There's a potential batch file fix (detailed here) - although you need to run autologon (which I can't) in order for it to execute:
Just add a .bat file to startup:
The latest BIOS (1103) from the FTP site fixes the issue, but breaks the ACPI drivers and SHE.
Now I get an XP-style loading bar on boot, but it's quick and doesn't need the standby hack.
Until ASUS fix the SHE and ACPI drivers I'm going to have reduced battery life and the blue Fn keys not working.
Now works fine with: