The opening theme is available through the Supermarionation Theme Page at Wanderer's (Jim Kaelin's) EarthStation1.
The closing theme song is available through the Supermarionation Theme Page at Wanderer's (Jim Kaelin's) EarthStation1.
Incidental sound files are available through the Super M Super Sounds Page at Wanderer's (Jim Kaelin's) EarthStation1.
For North American users, the Fireball XL5 theme can also be obtained from Patrick G. Kenny's TV Bytes Pages under Cartoons. Note that this site is sometimes unavailable.