Disk Recovery software

i need to recover data off my HDD, but i cant boot into OS X (10.4), is there any software which boots off the CD, before it gets into OS X?

You can use Disk Warrior.

You can try to boot from the system install DVD. That should mount the hard disk and allow you to retrieve your data. You can also use the Tiger installer to replace just the system and leave your data intact.

Does that mean it will repair the OS as well, if so how does it do it? also i read that the license was 'per MAC'. is there a license that can be used for several machines?

An "Archive and Install" replaces (does not repair) the existing system. There is an option to carry over user accounts and network settings from the old system to the new. That way you don't start from zero but if the problem is in your user account it can be carried over as well. Here's a link that explains things and also has a link specifically for doing this in Tiger: http://docs.info.apple.com/article.html?artnum=107120. I think there is a group license for 5 computers but I don't know the price. Check the online Apple store.