Which screwdriver bit do I need to take apart my mobile phone?

Question

It's a Sony Ericsson K600i and I want to take the front off.

Reason being, my 17 month old son got a hold of it while I wasn't looking, and gave it the full chew and drool treatment. Now, a few of the buttons won't work.
I'm not eligible for an upgrade until July, and I'm out of warranty, so a bit of guerilla phone maintenance seems to be in order.
The screws are ickle baby star shaped jobbies. I went to local focus, bought a cheap set of screwdriver bits, but the smallest star shaped on isn't small enough.
Had a quick look on screwfix.co.uk but I'm not sure of the sizes.
Anyone help?
Screwfix links are:
http://www.screwfix.com/app/sfd/cat/cat.jsp?cId=A435574&ts=21033
http://www.screwfix.com/app/sfd/cat/cat.jsp?cId=100193&ts=21941
I would like to keep the cost down too, so please don't let it be the expensive forged set...

I agree, after comparing it with the bits I bought from focus, the screw is smaller than the smallest star bit I've got.
On the screwfix website, this set (http://www.screwfix.com/app/sfd/cat/pro.jsp;jsessionid=PNHT4K45TNK0QCSTHZOCFFI?cId=100193&ts=43933&id=18983#) seems promising, but they have no sizes shown.
If you look at the enlarged image, do you think that the first on the left in the middle is the right one?

Answer 1

They're TORX screws. You can get a tool kit or individual bits from www.maplin.co.uk .(there may be a branch near you) or possibly from one of the market stalls specialising in phone bits.

Answer 2

Most likely it's a 1mm star driver.