Ubuntu UNR Image img vs. iso

[Refugio Rochin]

Hello,
I am trying to install Ubuntu notebook remix on my notebook using
VirtualBox by Sun.  I do not have a 1GB flash drive, I was trying to
save the *.img file to my hard drive, and then access it from a file.
However, the Virtual Box is not recognizing the *.img file.  I tried
accessing through floppy drives, and changing the extension from img
to iso, but it doesn't work.
What can I do.
I am somewhat of a novice...  Perhaps simply downloading the desktop
ubuntu will work, but I think the Notebook Remix version is more
suited for my ATOM processor on EEE PC 1000.