You can turn anything off or on in Windows 7 (just about). Best to get to Control Panel (if not finding it, just put in the search entry) and you will find it if not on the right hand side when pressing "Start". Indexing of files can be turned off, Restore Points can be deleted (but if anything goes wrong you have no backup to fix your system say like).
Right click on Computer and Open it. There you will find every logical partitionl of your harddrives and right clicking on a logical partition and selecting Properties by left clicking will bring up what you need. Disk cleanup will delete whatever you select and Control Panel and going through all the icons about will let you know what is in your computer and what you can do with it.
Windows 7 takes up that much room because if it ever goes haywire, there is a additional copy of Windows 7 stored on your computer and that is all. Of course you can make also probably around 3 DVD disks to store a copy also, because once Windows 7 is gone (done, corrupt, or whatever) that is all you will have to re-install or restore your computer.
I also make a backup on a different logical drive of the entire C: disk incase the Harddrive fails. All the other logical drives (partitions) on the same harddisk with data will be still readable and able to be transferred onto a new harddrive. But the C: drive is the one that is used the most and the one that will fail on any harddrive. That is why I never have the entire disk as the C:\ drive, if it fails (harddisk goes bad) everything is gone and done and can not be read. Partitioning off a harddive into logical drives on the same harddisk makes all the other logical drives and data good and can be read off of even used yet. But since the C:\ drive is the Boot Drive that starts up Windows, if it is failing, the computer will not start without having DVD's startup DVD disk or a copy of the Restore feature or start up feature of Windows to fix your computer.
Unless you want to buy Windows over and re-install the new registered Windows complete copy, and not an ungrade to Windows 8 whatever on a drive that can not be read after the harddisk logical partition C:\ drive (Primary Partition which holds the OS system) fails and can not be used anymore.