I have a Gateway with the same specs as yours. Ubuntu wouldn't go on mine either but I didn't fight with it - I just tried different distros until I found one that worked. You can probably make it go on if you try hard enough, I mean if you really want 7.10
1. Try your CD in another computer to make sure its good
2. You might drop down a notch to 7.01 version
3. Mint 3.1 went right on mine and it's Ubuntu in green with restricteds enabled up front
4. The new Elive looks very very good - E17 desktop
5. They are all free so try 10/15 of them -
http://distrowatch.com