After the stupid Inspiron 5150 died, we got the Asus Ezy PC. Then we relocated the HTPC to the study and started using Ethernet over Powerline to stream from the HTPC to the MP45-BDR. This set-up works ok and even has WAF.
Somehow we filled up the 2x1TB drives on the HTPC, so the question becomes, is the Next Project a NAS or is it a new media PC (Sandy Bridge?) to replace the one at Lorne? In particular, I am intrigued by the promise of WiDi 2.0, which might solve the problem of the bad connection infrastructure at Lorne.
In the end I went with upgrading the HTPC HDDs to 2x2TB HDDs. I used WD Caviar Greens (combination of low power consumption and "brand name" reliability) so now we have 4TB of storage capacity (plus the old 1TB drives can be used in the Next Project).
Switching over the drives was fairly standard but, partly for fun, I installed a new USB3.0 card, and then used a cheap HDD dock to transfer the files (max speed observed was about 49MB/s - not earth-shattering but much faster than the USB2.0 speeds I was looking at, plus now I can use USB3.0 devices).
Now to copy those archived files onto the new HDDs and fill them up too.