Since nobody answered, the only way to find out was to test the "LTS Hardware Enablement Stack" and see if it works or breaks ...
I installed Raring's stack (kernal + Xorg) with the following command:
sudo apt-get install linux-generic-lts-raring xserver-xorg-lts-raring
And reboot ...
The system booted fine and almost everything worked, even some-things that didn't work before, such as brightness controls. But one major problem showed up: with every other boot, Xorg consumed a lot of CPU capacity (about %25), and the system was super slow and laggy! I don't know what was the cause, but it was either a bug in Xorg or a bug in the kernel module for Intel GMA-500 graphics.
So I thought to try Saucy's stack in hope of solving the problem, since it has a newer version of the Linux kernel. The thing is that the kernel-package of Saucy is available but not its X-stack. According to this link, it is not a good idea to use a kernel with a different X-stack but in my situation I had no other choice, so I gave it a try ... I installed Saucy's kernel with the following command, and Raring's X-stack remained:
sudo apt-get install linux-generic-lts-saucy
And reboot ...
Everything worked fine! :)
Now all the problems of my Xubuntu-12.04 installation on the Sony VAIO P with Intel GMA-500 graphics are solved without the need for any tweaking:
- The screen works fine with the standard resolution and adequate performance;
- External VGA port works and secondary monitors are handled fine;
- Brightness controls work;
- Suspend/Resume works;
Now I'm a happy Xubuntu user on my Sony VAIO P which is way more faster and responsive than the standard Windows-7 which came pre-installed on it!
Of course there is one limitation: the graphics performance on Linux is much lower than the performance on Windows. For example, I almost can't watch any kind of video format on Xubuntu, while all video files with resolutions below HD (720p) play fine in Windows ... Although this is a problem I can live with, it would be really great to sea this fixed in Ubuntu-14.04 LTS.
Finally, my general recommendation is that if practical, do a fresh installation of the latest version of Xubuntu (which currently is 13.10 Saucy). When the next LTS version is released (14.04 Trusty) perform an upgrade or again do a fresh installation. But if your situation is like mine and you can't afford a fresh installation right now, installing Suacy's kernel with Raring's X-stack can fix a lot of problems.
Update:
Since the release of the 14.04 Trusty, the most recent LTS release, it is recommended to use its HES:
sudo apt-get install linux-generic-lts-trusty
Best Answer
I want to point out some basic facts about kernels, before giving answer to your question:
If your current (default) installed kernel is not working properly and you're getting some trouble then you can install any kernel you want and test whether it fixes your problem or not. There is no problem on using one or multiple Kernels at a time. But sometime you should consider the Kernel Mapping to your Ubuntu Version. For example following link lists out the mapping of different kernel to different version of OS:
1. Ubuntu to Mainline kernel version mapping
You can get a complete information of Kernel installing/removing from following link.
2. Kernel Mainline Builds
It helped me a lot to install a new kernel in Ubuntu 12.04.2. Now I can chose any kernel 3.5.0 or 3.8.0 from grub menu.
Following link illustrates how Ubuntu 12.04 LTS works actually. It illustates in very nice way, you would also like:
3. Ubuntu LTS Enablement Stack
Now coming to your point:
If you go through the 3rd link - Ubuntu LTS Enablement Stack, you will see Ubuntu 12.04.x LTS support and upgrade policy (enhanced view). Which states that the packages and kernels in Ubuntu 12.04 LTS will upgraded equivalent to non-LTS version. In short:
Since 13.04 is called raring, 12.04 is LTS and 12.04.3 is using packages equivalent to 13.04. This is the reason why 12.04.3 packages are called *-lts-raring-packages and the same you see in your repository. I hope your doubt would be clear. (Reply if still you've some confusion.)
This is because it is always good to stick with the kernel which best suits to your system. If your system is running fine with the kernel you are using, then their is no need to upgrade the kernel. But if you've any problem (as you can see, I had one that I solved after upgrading kernel as well as a lot of xserver-xorg packages) then you can consider to upgrade your kernel.
Thus Ubuntu uses the same logic and doesn't upgrade your kernel (it would be possible that same kernel version upgrades. Example 3.2.x will be upgraded to 3.2.y). Ubuntu doesn't want to take risk, it just left for you. :)
There is no any best way to upgrade a kernel. The way that worked for you is the best :)
I've mentioned the 2nd link, which you can be used to install the latest kernel. But I recommend you to install the kernel more specific to your 12.04.3 i,e 3.8.x which are listing in your repository.
You can install using the command. Just copy and paste following command in the terminal and execute:
Please note that the kernels and so as the repositories are frequently updated. So it would be possible that 3.8.0-34 will not be the latest version of kernel 3.8.x. In this case you can go for the 2nd method I've mentioned below.
or you can install it using Synaptic Package Manager. Type linux-generic-lts-raring and select it. It will automatically select all the latest -lts-packages to install. I'm posting what it shows to me:
Then just mark for installation and then Apply You can also get help from this link.