Are old updates needed?

Any updates that are shown in Add/Remove Programs are required - even updates of updates. If you remove them they will be downloaded again if you have Windows Update set to Automatic or offered again if you have Updates set to Notify, etc.

A number of Updates are Optional - I do not know for certain if these would be downloaded on Automatic, but I doubt it. When using the Notify option only the critical updates are flagged, but there is access to Optional Updates on the same page.

Bear in mind that for the most part they are security related - Critical updates will not be shown in Add/Remove because they cannot be removed.

.Net is another case - some programs require .Net to function and all versions are required. However it is unlikely that you require .Net 3. If you remove the various .Net versions you may find that you have to re-install if any of your existing programs cease to function.

If a piece of software is installed which requires .Net the installation will either include the appropriate version or state that it is required and give a URL from which it can be downloaded - or autodownload .Net.

 

It would be unwise to uninstall any updates - however you can recover disk space by deleting the uninstall files for those updates listed in Add/Remove Programs - if you do this you cannot subsequently uninstall the updates.

The uninstall files are in C:\Windows and are of the form $NtUninstallKBxxxxx$ where xxxxx is the KB number. As they are compressed files they should be coloured blue. You will need to Show hidden Files and folders under Tools > Folder Options > View.

To regain further disk space delete the temp files ....

Start > Run > %temp% > Enter. All files shown are safe to delete although a couple will be in use and cannot be deleted.

Delete the contents of C:\Windows\Temp with the same rider as above.

Empty Temporary Internet Files and set the max disk space to 50 Mb

If you have System Restore Enabled you can reduce the disk space allocated to this from the default 12% to say 6% - this will reduce the number of Restore points available.