Here are a few pointers on checking which version is installed.
If you are on a Laptop then you can probably assume that it is the HDD version that is installed (unless it is an EeePC)
If it is a motherboard based version then you can check for the following:
Look around the motherboard (probably in the bottom right hand corner) for a small circuit board soldered at 90 degrees to the motherboard, it should be about the size of a memory stick. If you can see one then you are most likely running the USB version.
Finally, if you cannot see any USB stick soldered to your motherboard then you are most probably running the SSD version.
You can also try downloading the latest update for your computer from the Asus website, if it has an MSI file inside it then you are running the HDD version and if it is a DFI file then you are running the USB/SSD version.
Good luck with everything
You may find that the way I have shown you doesn't work in which case just follow my instructions for adding the Terminal to your ExpressGate and type the following into the terminal:
Then select your resolution on the window that appears and click OK, it should ask you to restart and then it should work.
export DI_HAVE_RES_LIST='1024x768x24x60,1280x1024x24x60,<your res>'