Compression method

[NotAGolf]

I'm looking to backup a load of my videos, music and pictures. I've got hold of an old hard drive I can bung them onto but it's only 320GB which isn't big enough for everything so I was thinking of compressing the files so I can squeeze a few extra on (I'm talking about a compressed archive format rather than compressing individual files). 2 questions before I do this:

- Is it worth it? Obviously 320GB of data will take a while to package up so I don't really want to waste several hours for the sake of 5GB. (95% of the files are .avi, .mp3 or .jpg if that makes a difference)

- If so, what is the best format is likely to yield the most compression? RAR, ZIP, TGZ, TAR, 7z etc

Thanks for any help.

 

[NotAGolf]

Thanks for all the advice guys.

How much compression do you think I could achieve with PAQ8px HangTime? Much more than 5%? I don't have a problem with leaving it compressing for days if I get decent compression.

Hopefully I wont ever have to go back to it as it's just a backup, and I've already got my music/photos backed up on dvd's, but I thought if I've got some spare kit laying around I might as well make use of it. I cant justify the cost of another hard drive as I just bought a 1TB and the majority of stuff is already backed up.