Everyone who uses a computer should know what a .zip is
With a bit of luck you'll even know what a .rar is
But when it comes to compressing files, do you ever think about making a .cab ?
You may have seen a .cab as its what windows uses, but ive never considered using it, until a friend told me that he found it used less space that both zip and rar.
So testing this, compressing using www.PowerArchiver.com I compressed lots of files in the 3 formats and compared the results. To my surprise .cab came out the same or smaller, sometimes a lot smaller, on all the files. Since its a windows standard, most compression software should be able to open them too.
So I say give it ago yourself and see how much time and space you can save when your uploading files. I certainly will be msn'ing cabs from now on.