[Maccbean]

I got four new poulets yesterday afternoon.  Opened up the house this morning to find one, a Bluebell, laying down and she wont get up, she also sounds a bit gurgley.  I've no idea what it could be.  She's in a box on my desk still lying, slightly on her side.  I've booked an appointment for the vet this morning, but she seems quite ill so I don't hold out much hope.  None of the vets around me are poultry vets so pinpointing the right illness is a bit of a lottery. 

[joyfull]

if she sounds gurgly is she also sneezing and does she have any bubbles in her eyes, any facial swelling? Open her beak and have a sniff.
She could have mycoplasma in which case your vet will need to prescribe a broad based antibiotic such as Aureomycin, Tylan, Denagard or Baytril and you will need to get enough for all the chickens.
Chickens can have this from before they are hatched as it can be passed down from the hen to the chick when the egg is still inside her (if they have it you should never breed from them) and any stress such as new home, moulting etc can trigger an attack. You will never get rid of it but you can usually control it.

[Maccbean]

As I thought, the vet decided to put her down.  She couldn't stand and when she picked her up lots of liquid came out of her mouth.  She wasn't sneezing, just the gurgle.  I am worried about the others now though, although, none are showing signs of illness.  Do you think I ought to try and get some antibiotics to treat them anyway?

[joyfull]

the fluid could have been a sign of sour crop or impacted crop. If the others are showing no signs then don't worry but just keep a close eye on them for the next couple of weeks. If they show signs of the same thing then go back to the person you bought them off