It really depends on what you mean by very large databases. Is this a business application? Give us some idea of the size of the databases.
For example, I ran a database for an engineering business that covered shop floor data (Route cards to CNC, CAD & Timesheets), customers & prospects (3000 details), quotations, orders, invoicing etc The database for all this was below 40 GB and backed up every day! There were 14 terminals throughout the building. It ran on a very basic server via the network. 512MB RAM, 1.8 Ghz processor under XP. You could beat the spec of thatmachine with a budget of less than £800 today.