Advanced Server Clustering Question

I haven’t delved into clustering using Win2k Advanced Server, so I thought I’d post and ask a couple of questions…
We’d like to cluster two sizeable servers to replace some aging hardware, and consolidate the files from 3 servers onto one Win2k AS, then cluster it for redundancy. My main question is this, do the servers need to run identical hardware (ie processor, RAM, etc) or do I simply need to ensure they run the same amount of disk space? Any help would be appreciated 😉