Help, I'm going to need a filter but I'm not sure of the merits of those available....

MSR mini-works high flow rate but costs £80
Katadyn mini-filter cheaper but low flow rate £65
Katadyn hiker larger pore size so may not eliminate virus' £50
Pre-mac trekker does the lot but filters don't last long £70
Pre-mac pocket does the lot too but only 50 litres £22

will I need to worry about virus protection in the pyrenees or is that just for tropical locations?
any experience and reccomendations gratefully received

Nigel,

I've used Katadyn Pocket Professional which was really good, but on a heavy side. When looking into lighter alternatives I've seen reviews of Katadyn Mini-filter claiming that it is not only slow, but plastic cup is prone to breakage when considerable pressure is applied ... well, if it is slow it is probably happening quite often.

Right, problem solved.
I've just bought a "first-need" deluxe purifier for the princely sum of £50 marked down at outdoors from about £90. it comes with a 1lt sigg bottle and claims to remove virus's without the use of chemicals and delivers 1.8 quarts (litres) per minute. weighs about 400g (roughly the same as the MSR but the cartridge only lasts 500lts.

I used to use a Katadyn mini filter and it broke while filtering. OK, so I was applying considerable pressure to pump, because the water was a bit peaty, but I thought it was bad quality with a pitiful flow rate.
I now use a military one that screws directly onto an army water bottle, has a very fast flow rate, and filters out all viruses etc. Used it with no problem in the jungle, and no tubes etc to get clogged up. I can't remember how much it was, but it was bought from Silvermans.