Burn it to a CD-R and create a disc image CD, NOT a data CD. The file on Rapidshare is a NRG file, so you'll have to use Nero (either the full retail version of the trial version will work) or a utility like ISOMagic.
Also, be aware that once you upgrade to 2.0 you cannot roll the firmware in your HD-A1 back to a previous version. If you have any issues you'll be stuck with them for a while.