Aye acoustic padding is the way to go. You can get a practically silent HD by buying one of the quiet ones and you can get (i forget from where, possibly acasa) what is effectively a 5.25 mount for a 3.5 drive that surrounds it with foam padding - it really cuts out the high frequencys, (read whines) but temp goes through the roof.
Failing that, if you are running Linux (duh) and don't mind the load times, what is to stop you having a bit more ram and having something like /opt as a ramdisk? then you copy the game over at the start and run it entirely from ram. This does mean big load times (unless you can fit it onto a boot cd (dvd?) and have that copy it into ram), but it would be
much cheaper than gigabit ethernet.
Don't go for Zalmans though - yes they are quiet, but they generate a lot of heat and there are quieter, cooler fans out there. stop by places like tomshardware and anandtech and look at the comparisons, then head somewhere like overclockers.co.uk (if you are a brit) for the parts (I like oc as they sell the h/s seperate from the fans). I suggest one of the ones that bolts on to the m/b - you have to check compatability, but since they don't have to worry so much about the weight of the H/S, they can have a much bigger block = you can use a slower fan.
Just my thoughts (and no, I can't hear the noise of my PC

)[/i]