Ah well, the fan is easy enough to remove - its only held on by 4 (very easy) to slide off mounts (those 4 pointy bits at the corners - just slide them away from the fan). Now the next bit - this is a proper bodge job im afraid
But hey i dont have a windowed case (but doesnt look that bad) - i just took a very quiet fan and (using the bodgers favorite tool - zip tie!) i secured the new fan at 2 corners to the heat pipes! I'll post a pic if you're really interested! I reckon it would be very easy to fabricate a plexi mount type thing using the 4 original mounting posts though - next little mod maybe....
The results are silence and pretty much identical temps, give or take a degree, so im pleased!