Sparse Image won't restore to smaller Image.

Hi there;

Not entirely sure if this is where this question needs to be posted.

I'm in a little bit of a pickle. I purchased a Imac g5 1.6 ghz (2004) and want to install Leopard (10.5) on it.

I have a DMG copy of the installer but my problem was that the file is too large to be burned on a single layer DVD (i know I can burn it on a DL DVD, but I don't want to buy a pack of 5 DVD's and only need One). So I used disk utility and created a sparse image (8.7GB) and restore the DMG to that image. I stripped all the unneccessary files (languages and printer drivers). then I went back to create a 4.7 GB sparse disk image to restore the newly formatted DMG, but It still says that there is not enough space on the disk, when my Image is 4.7GB and the image is 4.45 GB.

My understanding is that even though i'm only using 4.45GB it still shows as the original 8.7GB even though i'm not using all that space

I'm currently running OSX 10.7.4 (lion) on my macbook pro and disk utility wont let me complete the task I have at hand.

I'm new to this so could someone help me?