This is my 20th GRUB theme! W00t!
Anyways, simpleBlue is a minimal looking GRUB theme while adding a bit of vibrant color. This theme is also independent from any resolution which means you can set it to any resolution and it will work fine, but at 640x480 things are a bit scrunched up.
Run the install.sh script in a terminal with root, then run through the few questions and you'll be all set. So in Ubuntu after extracting the files you would run
after you give the script execution permissions (right click on the file -> properties -> permissions tab -> click the text box that says "Allow execution of this file").
There is also a read me which addresses many questions I get a lot, but if you're still not sure about something I'll be glad to help. :)
Oh yeah, and I've included the XCF files for the menu, and little info pane in case you want to change the color.