before you chuck the pc out of the window (which may hurt your back ha ha
) ) think about your psoture at the PC - a lot of people slump down in their seats and hunch their shoulders over when they are at the computer - make sure you are sitting up with your lower back firmly supported and your chair adjusted to the right height. Make sure that you are not leaning forward over the keyboard as this puts a strain on your neck and shoulders -
Change your focus every now and then and look away from the screen to prevent tired eyes and get up and walk around every now and then to help the blood flow in your legs. (get a coffee or a juice! that'll keep you hydrated at the same time.
The final thing is don't cross your legs under your chair or in front of you as that can diminish the blood flow in your legs.
and yes as you can see from the above I have worked with computers for many many years and have no neck problems - I have a back problem (discs) but that was from an injury so I have to be careful - hope this helps!