The next step was to unwrap the Antec Fusion v2: 
I must say, it is an amazing looking casing. Removing the top cover lit by unscrewing the thumbscrew on the back, reveals the in-site: 
The next step is to replace the Antec I/O panel:
with the I/O Panel that came with the Gigabyte Motherboard:
This one looks a lot better also 
So, fitting the mainboard into the casing is a bit thight, but it fits, after replacing the Antec I/O Panel:
By the way, I did install the mainboard and all wiring before installing the cooler on the CPU:
The Ninja is taking up a lot of space in the casing, so it was installed last.
Up until now I did not install the ATI 3450 board, nor the wireless network card. After connecting power, a monitor, mouse and keyboard to the system I pressed the magic on button.......
The system booted, and by pressing DEL it brought me into the BIOS settings screen. In the BIOS setting - besides setting the time/date - nothing much had to be changed. To be honest, I forgot to write down exactly which changes I made. I put the Windows XP installation CD in the NEC DVD player and started installing the Operating System: Windows XP Professional SP2. This went rather smoothly, without any major hickups. During the installation I created a 20 GByte system partition to install the OS on. This enables me to install another OS without loosing all the data on the HD when needed.