PCA prcomp problem

I've just starting using the prcomp function, and I want to be able to extract
individual principal components (e.g. PC1, PC2) in vector format.  I haven't
been able to find any documentation that explains how to do this (or even if it
is possible).  Any help on the subject would be greatly appreciated.

Many thanks
Deirdre Toher
Teagasc National Food Centre