How can I copy the blockchain from my working client for use with a live CD savings wallet?
You can find the blockchain in this directory:

C:\Documents and Settings\YourUserName\Application data\Bitcoin (XP)
or
C:\Users\YourUserName\Appdata\Roaming\Bitcoin (Vista and 7)

As blk0001.dat and blkindex.dat. Copying those files to a proper folder on your Ubundu (~/.bitcoin/) should spare you from redownloading the entire blockchain.