How's your research going?
I wanted to build a similar system a little while back (but mine was just for NAS). You can read about it here: http://www.silentpcreview.com/forums/viewtopic.php?p=456178&highlight=#456178
I'm pointing it out as I wanted low heat and noise, and using a 45watt chip that you ask about, I managed to achieve this pretty well. So far the little box has clocked up over 1mth continuous uptime, and around 2months total.
Of course, you'll need to consider whether the 2.3Ghz will be enough to do everything you want it to, and still be "responsive".
With so many things on there, have you considered Data Security? I went for a RAID solution http://www.silentpcreview.com/forums/viewtopic.php?p=457377&highlight=#457377
although I still take periodic backups.
Hope that helps,