Hm. Without backups, I think the safest thing to do is not try to resize the Linux partition.
It is safe however to just make a new partition in the unallocated space. You could store data there for example.
If you have say a lot of music files, you mount the data partition at /data, and move your music files to /data/music. If before you had your music at /home/user/music, you could make a symlink from /home/user/music to /data/music:
By doing it this way, you can still read and write to files in /home/user/music, even though they are physically stored in /data/music.
ln -s /data/music /home/user/music
Anyway, just a thought...