ultra compressed file

Just had a call from a friend, she'd downloaded a 10 mb (yes, 10 megabyte) rar file, when it was extracted, out came a 3.49 gb (yes, 3.49 Gigabyte) iso image!!!
Ok, so i had to see this! Went hunting in google, found it, d/l'd it, and sure enuff, 9506kb, 3.49gb iso.
Anyone know how this compression can be acheived?
Hell, when i rar the iso back up, it becomes the same size 9.5mb, but rar another cd iso and that still about the size of a cd????
the file is called "Windows_XP_64Bit_6_In_1.rar" and is supposed to have 6 diff versions of windows xp 64 bit in the iso???
(hey, not interested in it being dodgy, just wanna know how the hell it's been compressed!)

The fact that you can re-compress the resultant iso to the original size indicates there is no special compression being used, rather it is the nature of the contents of the iso that allows compression to that degree.

Considering that it would be utterly impossible to compress a single XP installation, let alone supposedly six, into 10MB, and also considering what usually comes from "share" sources, I'd suspect you'd find some nice malware occupying that iso. A few viruses and trojans would neatly compress to 10MB...

I bet when you install that thing you'll end up with a bunch of viruses and spyware.
Yes there are *some* files that can be compressed very much (text files especially), but the XP image is not one of them:flames:

Or it directly connects to some computer you definetly do not want to be friends with.
HEH!

All your comments duly noted WELL!
I should have sat and thought about it, before posting the Q, eh? duh!