Sainsbury's....
Is my favourite supermarket.
I haven't used their Bio Powder, but have used the "colour" version (in the purple box of course). I like it.
MrAlex - I have the concentrated powder in a bottle, I have yet to use it, but the cool thing (besides 5 enzymes) is the bottle is an "auto dose" bottle, you just tip it upside down and dispenses a dose (20ml).
Also FYI - Sainsbury's own brand bio laundry gel is a Which best buy in the liquids category (2nd best, only beaten by Persil and beating Ariel).