Energy efficient PC for living room

Hi guys,

I am thinking of assembling a PC to be place in my living room. I will mainly use it for:
- Watching movies
- Listening to Music
- File server (for music, video , photos)

I am planning to leave it on 24/7 so I want it to be relatively energy efficient. I have ruled out an Atom 330 mini-ITX solution since it is extremely weak in cpu power and the energy benefit is not that great (at least compared to the performance sacrifice).

These are the parts I am thinking of using:

- Gigabyte GA-MA78GM-S2H 780G Socket AM2+ :it has a decent ATI HD3200 onboard so playing HD movies will not be an issue and *maybe* playing a game at the lowest resolution. £66

- AMD Athlon X2 5050e Socket AM2 45W Energy Efficient : It's a dual core and with low energy consumption and cheap. £50

- Corsair 4GB Kit (2x2GB) DDR2 800MHz/PC2-6400 XMS2 Memory Non-ECC Unbuffered CL5 :4GB is more than enough for what I want. £35

- Antec NSK1480 Slim Mini Desktop Case - With 350W 80+ Efficient PSU :it is slim and will not take much space in the living room. the small PSU will not be a problem unless I decide to upgrade the graphics(?). £50

I have an old Western Digital 200GB SATA hard disk which I will use and a 15'' TFT monitor, so these are all the components I need. The total price is £200.

What do you think? I don't know if the case+psu combination is OK for 24/7 use.. I have also read that it is not very quiet...