Number of IOs Per Second

I need to size a storage system. I know that I will have two tables, each with eight million records. I will have 10 users, each of whom will be doing complex reports simultaneously, each of which does joins against those eight million record tables.

What are some guidelines for best and and worst case, about the number of IOs per second that this system will generate? I need to make sure my RAID arrays have enough physical disks to satisfy this number of IOs.

If the database is 2 TB in size, what is the desired amount of cache memory?

-- 
Will
westes AT earthbroadcast.com