Bubbles in Space

Currently in the middle of exam study so when I need a break have just been playing around with this as a picture. Needs some work still. comments and crits
http://img12.imageshack.us/img12/551/backgroundbubblesy.jpg

Changed the composition a bit and gave it a background. The green bubbles have been put in to try and tie it to the background, still needs some work there. Any idea’s on how I can make it seam part of the scene and not just something slapped on top of a background?
http://img188.imageshack.us/img188/1555/backgroundbubbles11.jpg

Playing round with some different colours
http://img5.imageshack.us/img5/6864/greenbackgroundk.jpg