You shouldn't have to drill holes in the case to mount them, You can buy cheap adapters for the case. Although why? A 80mm fan is quite small, meaning more noise and less efficiency.
If you want purple LED'S try these.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
They're top end fans and do their job really well and are 120mm.
Although if you want green fan with purple leds it's going to be quite hard to find one as such, in that case it's not recommended but you can buy adapters.
http://www.newegg.com/Product/Product.aspx?Item=9SIA3TR...
-good luck, still reccomend the Corsair fans.