|It's got the black rectangular bracket sitting on the motherboard held down by 4 screws. The heatsink sits on the bracket and that in turn is held down by 2 plastic green clips.|
I just replaced the motherboard in a 4600 and had to remove the 4 bracket screws in order to get it out. And I just checked an empty 4600 case I have. It's got the 4 bracket mounting studs in the bottom panel--the one that also has the motherboard mounting studs.
Maybe cases made for socket 478 motherboards have mounting holes for bracket studs. The Dell case had 8 holes for two different motherboard styles. I believe they use the same case for their 2300 and possibly other models. So maybe generic cases are the same way.
There are three cables coming from the front panel--audio, USB and power/LEDs. You wouldn't absolutely need audio and USB hooked up. The power and LEDs go to a common proprietary harness and might be a problem as OtheHill suggests..
Ubuntu Cheeta, Ubuntu !