Your TreeSize details above look normal for a 475GB drive. You can see the majority of this space is consumed by what is in the Users Folder and related subfolders. This is where a lot of stuff from your Downloads, Music, MyDocs, MyPics are stored. Many people forget that other stuff needs to be stored somewhere. A good example is all your emails... this could be tiny or massive if your last 20 years of emails and their attachments are here. You can explore Users using TreeSize and get a real understanding of what you are storing and in what sub directories.
With 475GB on C, 206GB in Users and 158 GB free... is a workable system.
To better understand your C drive, you will need to explore how your C drive is structured. The way to do this is to use a standard Windows Tool called Disk Management.
Be extremely careful of what you do inside Disk Management, as you can easily destroy the structure and integrity of multiple disk drives and therefore also your PC.
You can go into Disk Management to review the information that is there.
Here is an example from my PC.
View attachment 23005
On the first line above, you can see my C drive of 465 GB (1).
At first glance you might not think the next 2 lines are relevant (2) ... but these are also part of the C Drive.
Further down, you will see a diagram of Disk 3. Note ... it is made up of 3 segments.
a. My C drive
b. 100MB Segment
c. 507 MB Segment,
View attachment 23006
I do not want to confuse the discussion by getting too detailed here. Segments will exist here for a variety of reasons. Often there may be a very large segment..... of unused space.... because when the drive was been installed the installer made a decision to use only, say, half of the disk and keep the second half for later use. It is also common to deliberately create 2 segments as a strategy, using the C drive for the operating system and the second segment for , say , data. The objective might be to be able to back up the operating system and apps separately from the data. Other elements may be there, because the disk maker might want to keep some housekeeping or techie stuff available on the drive for diagnostics, mtce, etc.
In my case... I am not in the least interested in trying to understand why there are 2 segments on my system disk... as 100+500MB is not worth the effort. If it was 100MB and 500GB ...I would be keen to understand what is happening in the 500GB segment.
As things stand .... you have a working C drive .... with the possibility that you may have more space available... but you will need to investigate further to understand what is actually there.
In parallel, you can check if there is stuff inside the Users folders which might be of no further use and can be deleted.
A viable option is not to do anything.... leave it as it is. Maybe by the time you need to do something 4 GB ssd drives might be so cheap that it might be easier to put in a newer, faster, bigger model.
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