Installing a dual boot of Ubuntu on your Vista laptop is really very easy, but there are a few gotchas that tripped me up and meant I had to install Ubuntu a couple of times to get it right. I am not a windows or linux expert at all, this is just a basic how to for beginners like me really, so comments welcome.
Dual Boot Basics Overview
Firstly an overview of the main elements involved and what is going to happen. The problem areas for me were disk partitions and boot records, these are the main elements involved in this process as they are shared by both Windows and Linux operating systems.
Master Boot Loader -> Grub
Right now you have a master boot record which boots you into Vista on your machine. This is going to be replaced by the Linux GRUB boot loader which at startup will give you the options of booting into Ubuntu or Vista.
There are other boot loaders for linux such as lilo, but grub works fine for me. There is a neat program for replacing the old master boot record that I will mention in a minute so don't worry about rolling back to your original Vista mbr (master boot record).
Disk Partitioning on Vista
You will also have your hard drive partitioned on windows into a few primary partitions. To check these partitions in Vista just right click on 'My Computer' or 'Computer' as its known now in less patronising vista, go to manage and disk management.
If you are doing this on your laptop you likely have a very small first partition named EISA Configuration, which can range from just a 500 meg to several gig. Its probably also 100% empty. Nevertheless I left this partition alone. From what I can gather it has something to do with restoring your laptop from a complete failure, so for safety sake I left this partition complete - the good news is that you can create enough partitions to install linux without disturbing this one.
There will also be another primary partition for vista to live on which you will need to leave intact. Plus perhaps another partition for another harddrive or something like that.
The main limitation with partitions on windows is that you can only have four primary partitions, so if you have 3 or more partitions on windows, you are going to be stuck to create 2 new partitions for Ubuntu and a linux swap.
Vista will let you get around this however with extended partitions. Essentially the fourth partition that you create on Vista will be generated as an extended dynamic partition so that you can create up to 60 logical partitions within this partition.
Insert your ubuntu disc and boot up your laptop. Linux should boot up automatically and you will see the Ubuntu desktop with an install icon in the top left. Proceeding through the install process is straightforward. Choose your timezone, your login details etc. etc.
When you get to the manage partitions section try manual. Selecting this option will let you see all the partitions you created in Vista. Select the partition you want to run Ubuntu on, format to ext3 or similar - there is one gotcha here, the mount point should be simply '/' for this partition.
Select your smaller parition and format as swap. Thats it. Move on through the installation and everything should be a breeze.
To note however, if you do not have an available internet connection during installation then the apt sources list [/etc/apt/sources.list] will be half commented out because many of the sources couldn't be verified at installation.
Perhaps something goes horribly wrong with your installation and you want to get rid of it. Uninstalling ubuntu and rolling back your mbr is not a problem though. Boot back into Vista, install a program called EasyBCD and roll back your master boot record. This will overwrite Ubuntu's grub loader and automatically boot you in to Vista when you start your machine.
Now all you have to do is format or destroy those partitions you created for Ubuntu to live on. As above, in Vista navigate through to manage partitions and the vista partition manager should be fairly straight forward to use.
If you are dissatisfied with your Vista install it is very easy to try Ubuntu out for a while and see how you like it. I actually prefer using Ubuntu for my work environment now that I have been using it at work for a while and encourage anyone to try a LAMP platform for web development.