Couldn't resist HPs £100 cashback deal on the N40L MicroServer so I took the plunge in early November 2012. This was to replace my ailing ZyXEL NSA-220 NAS box. Took the 2 x 750Gb drives from the NAS and added a couple of spare drives I had kicking around into the HP. All went well until I tried to use the eSATA port and I was going nuts trying to get it to work (thanks to all for the revised BIOS, etc) - eventually turns out that the eSATA port was fooked, rang HP and they sent a new motherboard next day, excellent service.
So now I have:
HP N40L Microserver
4Gb RAM (added a cheapo Corsair 2Gb from www.dabs.com/679N - works perfectly)
2 x Seagate 3.5" 750Gb - RAID1
3 x Maxtor 3.5" 320Gb - RAID5
1 x Hitachi 2.5" 160Gb - OS drive
1 x 320Gb Freecom USB HDD for backups
Keane USB FM Transmitter (www.keene.co.uk/multi.php?mycode=USBFMT) - added for a cheap way to send audio throughout my house, well, certainly cheaper than Sonos kit!!). It will suffice until I win the lottery. It works quite well but you have to frig the remote desktop settings to get it working properly.
Adding a Radeon 5450 VGA card soon (for HD output to TV in other room for movie viewing, as it should be better than playing via the noisy PS3).
It's working great for media serving, using either iTunes ('cos the other half likes using iTunes) or Subsonic (which is excellent for mobile/tablet, etc) for music, am going to try and get working as a mail server for outlook next (wish me luck).
My total outlay has been £129 for the server (after the cashback), £10 for the memory, £40 for WHS2012 software), £15 for the USB FM jobby and £20 for the HD VGA card - total of £214 for a cracking system so far, it's certainly quicker and quieter than the old NAS (which was flogged on fleaBay, naturally).
A big thanks to forum users as the solutions on here have been very helpful.
Cheers, dickie.