|"What is C:\System Volume Information?"|
The answer to that is easily found by searching the web.
System Volume Information Folder
"If you've done much wandering around in Windows Explorer you might have noticed a folder called System Volume Information and wondered what purpose it serves. It's actually a part of System Restore; the tool that allows you to set points in time to roll back your computer. The System Volume Information folder is where XP stores these points and associated information that makes them accessible."
"How many System Volume Information folders your computer has and where they are located depends on the settings you've selected for System Restore. For an overview of System Restore and how these interactions apply, click here."
(When you click on "here" it's a link to:)
How to gain access to the System Volume Information folder
"The System Volume Information folder is a hidden system folder that the System Restore tool uses to store its information and restore points. There is a System Volume Information folder on every partition on your computer."
I have never had ANY need to access a System Volume Information folder's contents on ANY computer.
Some people may be looking for something to get rid of because they have a C partition, or whatever the drive letter is of the partition Windows was loaded from, that's too full, and / or if they have enabled showing hidden files and folders, they may notice the System Volume Information folder's contents can take up a lot of drive space.
"How many System Volume Information folders your computer has and where they are located ...." and how much disk space is used for the restore points which directly affects the size of the System Volume Information folder "....depends on the settings you've selected for System Restore
See the System Restore info at the link above.
(Note that it's recommended you DO NOT select the drive letters of removable drives that you're likely to remove, because in that case, the info in the \System Volume Information folder on that drive is likely to have restore points that won't work.)
You can reduce the amount of space it takes up by using the Disk Cleanup tool - one of it's options deletes all the System Restore restore points except the last one.
Or, you can chose to turn off System Restore, which will delete all the System Restore restore points
(You can't delete individual restore points when you use System Restore to do that unless it's the only one or the last one.)
I don't recommend either option if you want to be able to use System Restore to load restore points when something in Windows gets screwed up and you can't figure out how to fix the problem.
System Restore isn't perfect - it doesn't back up everything - loading a restore point may not fix your problem - but it's built into Windows and you might as well leave it enabled, in case you do need it at some point - it's worth a shot trying loading a restore point if you need to.
In any case, there is a limit to how large the System Volume Information folder gets. Older System Restore restore points are automatically deleted as time goes by, and you can specify the max space System Restore can use for the restore points. (See the System Restore info at the link above.)
By the way, when it's suspected you have malware - viruses, trojans, root kits, spyware, etc - on your computer, you often are told to turn off System Restore before you use an anti-malware program.
(Most malware these days is NOT a virus.)
According to Microsoft experts, that''s NOT recommended, because anti-malware programs have been known to remove the wrong things when you have it remove malware it finds (e.g. Spybot, AdAware, many times), and in some cases you can't fix the damage done unless System Restore is enabled and you have (a) restore point(s) to load.
Their argument is that your Windows installation cannot be re-infected from malware that is found in a System Restore restore point, unless you deliberately load that restore point yourself.
They recommend that you DO NOT turn off System Restore BEFORE you remove the malware. When you have removed the malware and have found that everything is working fine, THEN, if you want to, you can turn off System Restore to remove any malware that was found in the restore points, then turn it back on.
You DO NOT need to turn off System Restore to remove malware that was found in (a) restore point(s) unless you think it's possible you might need to load a restore point, and even in that case, you can often find ouit which restore point(s) NOT to load and not have to turn off System Restore.
If the anti-malware program DID find malware in restore points, they will be at the location (drive letter):\System Volume Information\.... (some specific location). If the anti-malware program makes a log file or some other record of what it found after you have used it to remove malware, you can look at that file, and if you need to load a restore point, that info will tell you the exact location of the one(s) that is (are) infected - if you need to, you can try loading any other restore point without risking being re-infected by the same malware.