I spent an hour at the shop test sitting my chair - I bought a magazine to read. It then took me about a week of fine tuning the adjustments to get it perfect for me - never touched it since (1 yr later) and I no longer have any back/neck/shoulder pain.

Also, the chair is only 1 part of it - you need to get your desk, keyboard, monitor height/distance, correctly positioned too.

__________________
MY09 Evo X - 1.6bar@3500rpm - got lag?
Barbagallo - 56.03 (S); 1:08.09 (L)
Collie - 50.77
Possibly the most under-driven Evo X in the world??