Should I run Ubuntu alongside Windows or in a virtual machine?

I would like to install Ubuntu on my Windows 7 64-bit PC to do analysis of astronomy data. The data files are often large (can be few hundred MB, possibly a GB). The data files may be located on an external hard disk. The PC has 6 GB RAM and 670 GB hard disk.

I'm trying to decide whether to do a proper dual-boot, installing Ubuntu in its own partition (I'm nervous of messing around with the hard disk, have never done it before) or to run Ubuntu using VirtualBox in Windows. How much slower is running in Virtualbox likely to be?

If I do go for a traditional dual-boot, would it make sense to divide the hard disk more or less equally between the two OSs?

I would be very grateful for some advice.

Many thanks Kevin

If the application you will be running is CPU and RAM intensive then it will be best for you to install Ubuntu natively rather than virtually. If you do decide to dual-boot and will only be using Ubuntu as a secondary OS there is no need to give it such a large partition unless you will be storing large files on the partition itself (but you said that your files were on an external HD). Ubuntu would be able to access the windows partition (NTFS) if you wanted to store things there anyway. Therefore you should give the Ubuntu partition ~20GB (to be on the safe side) and it will also require a swap partition that is the slighlty larger than the amount of RAM you have.

If you will only be using Ubuntu temporarily then you may want to look at Wubi which will simplify the installation and removal by doing it from within Windows. The downside of Wubi is that read and write speeds to the HD are slightly slower. This may not bother you.

You are right to be cautious. Installing an OS can cause problems.

What I suggest:

First - Run Ubuntu live. This allows you to test your hardware and decide if you want to install Ubuntu. Keep in mind, it will run a bit slower when running from a CD or USB.

Second - If you decide to install, back up your data first.

Third - Resize your windows c:\ partition with the partitioning tools withing windows 7. Leave the resulting free space unformatted.

You could use the Ubuntu installer to partition your hard drive if you wish. You might get complaints from windows if you do (which can be fixed).

The read the install guide, make sure you understand how linux identifies partitions (/dev/sda ...) and install Ubuntu. Personally, if you have the space, I would suggest 40 Gb for Ubuntu. You can easily use as little as 10-20 Gb, and I have done installs on as little as 3.5 Gb, but it is not much fun to run out of hard drive space and I am guessing you can easily spare 40 Gb or so.

https://help.ubuntu.com/community/GraphicalInstall

As long as you do the preparation the risks of data loss or other problems are minimal. People seem to run into problems when they rush to install without understanding the install process or when they use the advanced options of the installer (to change the defaults) without understanding what they are changing. The defaults work just fine for the vast majority of people and you should not change them without understanding the changes you are making.

If you too worried to mess with partitioning, you can install WUBI. Wubi is an officially supported Ubuntu installer for Windows users. It can install and uninstall Ubuntu in the same way as any other Windows application. It's simple and safe. Run the download file

If you need any extra help, take a look at the Wubi Guide or ask a question in the Wubi forum.

After the file is downloaded, you have to open it to run the installer. You will find the detailed instructions below. If you need further help, the various support options are listed at the bottom of this page.

If you are using Internet Explorer, you'll be asked whether you want to run or save the file. Choose 'Run' to launch the installer.

Most other browsers, like Firefox, will only ask you to save the file. Click 'Save' and then double-click the downloaded file to launch the installer.

3.Install it

If a security message like this appears, click 'Continue' to proceed with the installation.

To install Ubuntu, all you need to do is choose your username and password. Please note that you have to enter your password twice to make sure you typed it correctly.

After choosing your password, click 'Install'. The files will be downloaded and installed automatically.

Wait until Ubuntu is downloaded and installed. Please note that the whole process can take a while – the downloaded file size is 700MB

When the installation is complete, you will be prompted to restart your computer. Click 'Finish' to restart.

After your computer restarts, choose 'Ubuntu' from the boot menu.

http://www.ubuntu.com/download/ubuntu/windows-installer