or you get an understanding that not all customers have the same screen, so customer of ocuk will be on screens with their brightness turned all the way down and contrast levels slightly lower then normal, which would make it harder to see. there is so much information on a single page i forget how much each visitor takes in but it's so minimal. you don't want to go making things blend better too much when you're paying someone to make a banner which sole purpose is to grab their attention. geesh
to put it simple - i can see it fine. can you be sure customers can when it's being used and not put up for us to examine? with the op's example you have a much better chance that they will be able to easily see the image.
i also made the image to show how the mouse clearly fades into the black. the colours go from light to medium to darker to black. maybe you're the one who needs a new monitor.
alright i'm off to bed
edit: another example of the different contrasts. top is yours, bottom is op's. i used green to show it better. the middle green block stands our far better then it does on yours. someone with a lower contrast monitor will less likely see the darker shades and think it's all one colour which would lose the mouse, so therefore the op's is better and all that.