how to store and retrieve large number of x,y points

I am building a database driven web client. We are storing many many x,y plotted points and I was wondering if anyone had any experience doing something like this and could give me some advice as to the best course of action for efficient storage and retrieval of these points.

Some methods discussed so far are:
Text stored in dB, perhaps csv separated
XML text stored in dB
Colums to identify points for a given object for instance we have a line that could have a thousand points

Thanks.

[512 byte] By [TBrij] at [2007-12-22]