What version of Windows do you have?
Why are you not able to have Windows updates installed?
What version of SolidWorks is your school using?
If the school is using later release - you would not be able to open work done at school on earlier release.
I'm not sure if you can get the older version available to download. Further student versions are valid for one year only, so not sure if you can use your current license for older version or not.