[R] Question about 'text' (add lm summary to a plot)

[Dan Bolser]

I would like to annotate my plot with a little box containing the slope,
intercept and R^2 of a lm on the data.

I would like it to look like...

 +----------------------------+
 | Slope     :   3.45 +- 0.34 |
 | Intercept : -10.43 +- 1.42 |
 | R^2       :   0.78         |
 +----------------------------+

However I can't make anything this neat, and I can't find out how to
combine this with symbols for R^2 / +- (plus minus).

Below is my best attempt (which is franky quite pour). Can anyone
improve on the below?

Specifically, 

aligned text and numbers, 
aligned decimal places, 
symbol for R^2 in the text (expression(R^2) seems to fail with
'paste') and +- 



Cheers,
Dan.


dat.lm <- lm(dat$AVG_CH_PAIRS ~ dat$CHAINS)

abline(coef(dat.lm),lty=2,lwd=1.5)


dat.lm.sum <- summary(dat.lm)
dat.lm.sum

attributes(dat.lm.sum)

my.text.1 <-
  paste("Slope : ",     round(dat.lm.sum$coefficients[2],2),
        "+/-",          round(dat.lm.sum$coefficients[4],2))

my.text.2 <-
  paste("Intercept : ", round(dat.lm.sum$coefficients[1],2),
        "+/-",          round(dat.lm.sum$coefficients[3],2))

my.text.3 <-
  paste("R^2 : ",       round(dat.lm.sum$r.squared,2))

my.text.1
my.text.2
my.text.3


## Add legend
text(x=3,
     y=300,
     paste(my.text.1,
           my.text.2,
           my.text.3,
           sep="\n"),
     adj=c(0,0),
     cex=1)