If you are seeing Ubuntu GPG Error BADSIG use the one of the following methods to fix
Error Message:
W: GPG error: http://archive.canonical.com intrepid Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key
Try to run the following commands from terminal
sudo -i
apt-get clean
cd /var/lib/apt
mv lists lists.old
mkdir -p lists/partial
apt-get clean
apt-get update
source
Mount ISO File
First you need to make the directory to put the ISO file into using the following command
sudo mkdir /media/isodir
Then use following command
sudo mount your_image_file.iso /media/isodir/ -t iso9660 -o loop
Now you should have your iso file mounted, and accessible from your desktop.
Unmount ISO File
Just use following command
sudo umount /media/isodir
Net Applications, a Web site analytics company, just published their April 2009 Web users survey, Market Share, and they found that “Linux usage share on client devices has surpassed 1% for the first time and we still have 99% to go and i think it can make it , thanks to some powerful distributions like Ubuntu,Fedora and OpenSUSE.

So finally i got free time to upgrade to new Ubuntu Jaunty 9.04 , i was using Ubuntu Hardy 8.04 for long time and it was awesome but now its time to move , and here some new features i liked or noticed at first use for the new release :
- New Ext4 file system support
- Faster boot time almost 20 sec “wow” check this video
- New network manager and its way better and easier comparing to 8.04
- Nautilus 2.26.2 and tabs thing very useful
- New notification area which rocks

- The shutdown/restart/suspend options have been taken off the System main menu
- Wallpaper transformation
last thoughts :
comparing to 8.04 its way faster,better and sexier
, and here is my desktop final look
