Say vs. Speak

Hi teachers,

Please look at the following:

[color=blue]I spoke to John yesterday.
I talked to John yesterday.

What is the difference?
Could you shed some light on how to use say and speak?

Thanls in advance

Jupiter

Here are two threads that will be of help:

Speak vs say
[size=75]http://www.english-test.net/forum/ftopic831.html[/size]

May I talk with Alan?
[size=75]http://www.english-test.net/forum/ftopic5827.html[/size]