- You should download the sage-5.8.ova file from one of the mirrors in http://sagemath.org/download-windows.html
- After that import the ova file into virtualbox by using the method outlined in http://wiki.sagemath.org/SageApplianceInstallation
This should get your sage installation up and running. For more information on how to work with the virtualbox installation, look up this page: http://wiki.sagemath.org/SageAppliance
To migrate your worksheets from sage-4.7 to sage-5.8
- Create a shared folder between your sage-4.7 in virtualbox and your Windows.
- download all your worksheets after starting sage-4.7 (you can select "Download all active" from the Home page) and save them in that shared folder. It will be in zip format.
- If you have archived worksheets, then you need to download them too.
- In virtualbox set up the same shared folder between sage-5.8 and your windows.
- Start sage-5.8 and upload the worksheets by selecting "Upload" from the Home window and then select that zip file that you downloaded earlier.
- Ensure that all the worksheets you need have been transfered. After you are convinced that you have done everything correctly, you can go ahead and delete the sage-4.7 installation.