ah well, ive scoured the internet for an answer and found nothing, no matter, ive just resized the images to the same size, which i think looks better.... well, thanks for all the help! 
bear with me, i have an idea, one sec...
i have the solution! it involves no change of code really, all you have to do it take the original logos, size thre background up and put the logos in the corresponding corners, so you have a 75px logo in the bottom right of a 120px square, then for the mouse over have the same sized background (120px) and then just size the logo up to around 100px, genius!
sorted, uploaded,
link
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