Oil pressure gauge wonderings

[dneuman@stars.sfsu.edu (Daniel George Neuman 2)]

Hello All,
I have some questions about the oil pressure gauge in my car (69 2000).
First do they work well??  What should the gauge be saying at idle with
a warmed up car??  What about at higher rpm's??
When my car is warmed up and I am idling ~800rpm my gauge reads really
low on the scale?  Is this normal??

                thanks,
                        Daniel