How to resample continuosly time data to be represented real time ?

Hi,

   I have a simple question. I am plotting on a chart
   a series of values.

   These values arrive irregularly but continuosly, during a long
timespan, one after another
   (for instance 1 each second or 2) and they may be a few millions of
values.

   I have to recreate a real time plot of these points every few
seconds.

   The problem is that I need:

      1. My list of values in memory, used to draw the chart, cannot
exceed, say, 500 values.
      2. Represent the values observed up to a given time, clearly
sampled, but without (big distortions)

   What can be a simple strategy of continuous resampling which
   allows me to have at any given time a fine representation of
   the values observed up to that time ?

   I have tried simple stupid resampling scheme like removing the
values in
   odd places when the count exceeded 500, but this causes eccessive
   smoothing at the begin of the chart.

   I have also tried removing values using an interval equal to the
current timespan
   divided by 500. But this also causes eccessive ridiculous smoothing
at the end of the chart !!

   I feel so stupid! What the right way to do that ?

   -Pam