correlated binary data and overall probability

Dear All,

I try to simulate correlated binary data for a clinical research project.
Unfortunately, I do not come to grips with bindata().

Consider
corr<-data.frame(ID=as.factor(rep(c(1:10), each=5)),
        task=as.factor(rep(c(1:5),10)))

[this format might be more appropriate:]
corr2<-data.frame(ID=as.factor(rep(c(1:10),5)),
        tablet=as.factor(rep(c(1:5),each=10)))

Now, I want to add one column 'outcome' for the binary response:
* within each 'task', the probabilty of success (1) is fixed, (say 
rbinom(x,1,0.7))
* within each 'ID', the outcomes are correlated (say 0.8)

How can I generate this column 'outcome' with the given proporties?

Many thanks for hints or even code!

Regards,
Christian