It doesnt delete anything that you will need it basically moves files around and gets rid of left over files and makes your hard drive cleaner, this makes it easier to read and find things it needs so it runs faster!
I would do it weekly to be honest, the more often you do it the less time it takes
Thanx Nick, I did it last week and did Did Take Ages But Why I was Confused it that afterwards My Windows messenger was The OLD Type.
So I was wondering if It got rid of the new type.
Anyway I Downloaded The New one again.
So it would seem that my Windows messenger changing would have nothing to do with The Defragg after your explanation so I don't know what happened there.
It's odd that the defrag process would result in an application change like Windows Messenger reverting back to an older version - infact, I've never heard of anything like that! Might have just be a coincidence, or maybe certain files that are used by the new version became corrupted or something (but even then, the new version should have just attempted to run and failed, rarther than reverting back?!) How strange! That reminds me, I need to defrag my machine at home!
Still haven't defragged my machine! Thing is, I've got so many hard drives in here that it might take a while for all of 'em! (actually it probably wouldn't as all but one are "fresh" in and don't have much on to be fragged) but I could still do with doing it!