Upgrade Ubuntu from wubi.
 

I have Xubuntu 11.10 and want to upgrade to 12.04 LTS. My network connection is slow and it says it needs around 10 hours to complete the download if I upgrade using the update manager. It is not possible for me to keep my computer close to the network for so long. I cannot use Live CD as I don't have a CD writer. Is there any way in which I can download the 12.04 ISO and upgrade my existing Ubuntu using wubi from Windows?

[I had installed Ubuntu from Wubi].

Try unetbootin it can be executed from windows or linux download Dvd
http://unetbootin.sourceforge.net/

I know about Unetbootin. I had used it once. But I think it is only to make Live USB.

Are you sure Xubuntu Live USB will detect my current installation? [I only know that Live CD'd can detect current installation and upgrade]...

Have a look at the following links. I have no first hand experience with upgrading a wubi install so please take the proper precautions.

http://ubuntu-with-wubi.blogspot.com...i-install.html

This link provide the howto
https://help.ubuntu.com/community/Lu...e_CD.2BAC8-DVD

This link provides the alternate CD image.
http://releases.ubuntu.com/precise/

I will give it a try and post what I get out of it....

Actually, the correct URL is: http://cdimage.ubuntu.com/xubuntu/re...12.04/release/as I have got Xubuntu...

Unetbootin is also used to install os.

But first, I will try the process given by michaelk. It will take me some time to download as the connection is slow. So I will post the outputs after some time.

I have installed OS using Unetbootin before, but in this case, I want to upgrade. I wonder if Live USB will detect my existing installation.

Finally, the download has completed. I had mounted the iso but what ti do after that?

run the command
gksu "sh /cdrom_mountpoint/cdromupgrade"

Sorry for the extremely late reply. Actually I wanted to upgrade after finishing all my important work so that I do not have to bother about losing my files.

But
gksu "sh /cdrom_mountpoint/cdromupgrade" is for Ubuntu and I use Xubuntu. What is the command for Xubuntu?

Yes...I have been able to start the upgrade after mounting the image file. Acctually in place of 'cdrom_mountpoint', I had to write the mountpoint. But, again the 'Distribution Upgrade' is asking me to download around 500 MB. How to I skip this download...? (The reason for which I chose alternate CD upgrade was to skip this download)

Sometimes the newest version after downloading has updates placed in repositories before the cd or iso is updated.

But how do I skip those updates....or do I have to download a fresh iso once again...?

The daily updates are only a few MB. If you don't update for a longer period of time this will of course be more (which means that after the install you will have one big update). You shouldn't skip those updates, they contain bugfixes and, more important, security updates. If it is not possible to download those updates, because of your slow internet connection, you should consider to change the distribution to something with less updates, like Debian Stable or Slackware.

Can I download all the updates from torrent and install them like a deb file?....I mean, is a file available on the net which contains the updates which can I download and install?