A live system doesn't touch your installed disk OS an any way, honestly.
No disk partition is mounted by default, all the OS is on cd or memory stick and run in your RAM.
That is the reason, why you can launch the live system and repair an installed OS, but only if you want to do.
With a live system you can also save files from hard disk (linux and NTFS also), you can restore, and
you can just try and play with a live system without use any hard disk.
You said, you have many updates?
Did you consider to download an actual 'Daily Build' from last night or finally SL 11?
This is a live system also you can find it here:http://mirror.de.sabayon.org/iso/
-Linuxfluesterer (I love KDE ...)