legends on the outside of the "box"

Hi R People:

Here is a simple set of commands:

x1 <- 1:10
x2 <- sqrt(x1)
plot(x1)
points(x2,col="red",pch=3)
legend(2,8,legend=c("First","Second"),col=c("black","red"),pch=c(1,3))

Fine.
Now, I would like to put the legend box on the outside of the plot itself, 
perhaps in the lower
left hand corner.

I've been messing with mtext, but to no avail.

Any help would be much appreciated.

R Version 1.9.1 Windows
Thanks,
Laura Holt
mailto: lauraholt_983 at hotmail.com