Compress Disk to save space?

i was just wondering if Compressing disk to save space is a safe thing to do. I found the setting in properteis in my local disk C:. I thought this would help save some space on my computer but is it safe to do.

it does not save u much space at all. it also slows down the comp as each time the comp wants to use the file it has to uncompress. u should only do this as a last resort

it doesnt save much space because the compression method sucks. Microsoft should use the LZMA compression

Compression is alright for things like "C:\WINDOWS\ServicePackFiles" and other folders/files you'll more than likely never open. I've compressed some folders/files that I don't use that however may be needed by Windows at some time and have saved about 300MB disk space.