Advice Please: How many downlighters?

[Ponty]

In the process of doing out my living room after recently moving in readiness for home cinema etc.

Not having had downlighters before, can someone tell me how many I would need to adaquately light a 5.2m by 3.5m room?

I was thinking 3 pairs (6) of 50W but wife likes a 5 pattern. I would rather have too much light and be able to dim, than find 5 is insufficient?

Am going for mains voltage not low voltage.

Thanks

[Ponty]

Bump, thanks for the replies...

[BruceH]

My Lounge / Cinema is about the same size.

I have 12 downlighters, 3 rows of 4.
They were originally all going to be 50w.

Then I realised that the Futronix P400 only support 300w per channels and I had the centre row on one channel (4 * 50W OK)
The outer two rows are on another channel (8 * 50W - Oh dear).

I have dropped the outer rows to 35W (8 * 35W OK).

So anyway, what I am saying is 12 * 35W is probably enough.
8 * 35W + 4 * 50W is definitely enough.