The fan headers on the motherboard are slightly offset to take either 3 or 4pin fans, they will only lock in one position.
If you already have two IDE HD's then that's another good reason to get a new SATA DVD drive in black to match the nice new case.
One other thing I'd do is switch the orientation of the CPU to blow front to back instead of bottom to top as it is now. This way the rear case fan will remove more of the heat from the CPU and you'll have a cooler system as a result, it's not nessesary though.
If you already have two IDE HD's then that's another good reason to get a new SATA DVD drive in black to match the nice new case.
One other thing I'd do is switch the orientation of the CPU to blow front to back instead of bottom to top as it is now. This way the rear case fan will remove more of the heat from the CPU and you'll have a cooler system as a result, it's not nessesary though.