Free up some space on C:\ drive when its critical.
The following article displays how much space you can gain by freeing up some space on C:\ drive by deleting or moving the files/folders.
Note: SFC and WFP uses to restore corrupted System ModulesCan be moved to some drive and using Registry we can set the DllCache location in another drive. So when next time WFP runs it searches for DllCache folder on drive specified in registry.
6. C:\Documents and Settings\Users
11.C:\Program Files\Support Tools
21.C:\Winnt\ *.MSI files
I will shout more if I have something more to add in here...