SQL2008 and clustering

All,

I am looking to create a SQL2008 cluster (on win2k3) but in 2 steps.. i need a working SQL2008 initially then adding in a node to have it in a clustered setup. Is it possible to install in a 1 node cluster initially with a view to adding in a 2nd node in an active/passive configuration...??

All comments and help welcomed.

TIA
Nels