Initial cluster setup

I have the following grid based resources and am curious as what kind of load ability I should expect from it. Also any recommendations on how I should use or reallocate them these resources.

1 Cluster Manager/Primary DNS/NFS
20% CPU, 512MB RAM, 160G drive, 2000G BW, 4IP’s
2 Nodes for Web
20% CPU, 1G RAM, 80G drive, 2000G BW, 4IP’s
1 Node for Database
20% CPU, 2G RAM, 80G drive, 2000G BW, 4IP’s
1 Secondary DNS
768M RAM, 30G drive, 1000G BW, 4IP’s

I currently run cPanel on the secondary DNS box, but am curious how to let Interworx use that for pushing DNS updates to.