30+
Windows 7 Ultimate 64-bit with SP1 English (no additional language packs) + updates
~30 GiB - C:\Windows
~0,6 GiB - C:\Program Files
~1,2 GiB - C:\Program Files (x86)
- Windows Update will store backup files on the system partition.
- Applications use Application Data on the system partition (C:\Users\Username\AppData). Check redirection of folders.
- Indexing Options
- Volume Shadow Copy services (should be enabled; built-in Complete PC Backup)
One may probably still be able to delete or move Windows Update backup files. The service pack uninstall files were possible to move in previous Windows versions, at least (involving path edits in the registry as per some Microsoft KB article).
~ I manually excluded non-typical applications for this estimate (but not Common Files). However, I have various MS SDKs installed which might have installed various system files in C:\Windows.