If the command that runs right after initial powerup (on pushing the left power button) in the BIOS could somehow be remapped to load a GRUB bootloader while the right power button would just initiate the standard MBR which would load the M$ bootloader (BCD) then this might be how to make this possible. My big brother used to know how to hack into BIOS images and manipulate them. He's a very busy programmer now so getting his time is hard but I should ask him if he thinks this task is feasible, and even if he might even know where one would start at trying to figure out how to make it possible. My feeling is that if this mapping is done in the BIOS image that this might be possible to change with an altered BIOS image but if the mapping to a command is done using some other protocol or done on the hardware level, then it might be impossible to remap it. If one even knew what the command was that gets initiated, you might be able to make that command instead load a second alternate MBR type file which would load a GRUB bootloader. Because if you had a GRUB bootloader that had Ubuntu set up as the default OS set to load in 1 second, and then you still had the standard MBR which loaded the M$ (BCD) bootloader and Windows 7 would be the default OS on there set to load in 1 second, then this would be ideal.
From what I understand, Express Gate is just an image file on the hard drive and some command possibly starting from the BIOS invokes this image to be loaded and ran. People have manipulated this Express Gate image file (in other forums) as well to change functionality of the Express Gate OS, so this might be a potential place to re-direct in the begininng before it executes the running of whatever script or code loads Express Gate, and instead run a command to load GRUB from. Need more research.
I DO believe this would be super cool to engineer this function into my new 1005PR, but the question would be is itworth the time to figure out HOW to do it? I see a lot of people here asking for the same thing (ie they want their pizza delivered in 30 mins or less), but how many of these people asking are willing to pitch in and help do the research because I too am busy and I do not have gobs of surplus time to figure this out all on my own. If everybody does research and Googles a lot with me we might have a chance at figuring this out. Perhaps as a far-fetched last resort if we could find some contact at ASUS who could even offer some insight as to this issue.