At Crossett Brook we have established a 2-year leasing program for replacement of our lab computers.  Our lease with Compaq ends with a $1 buyout if we choose to keep the machines (we will!) Although we do end up paying more over time (interest adds up to about one computer per year), there are several reasons why we decided to lease:  1) This allowed us to purchase a larger number of identical machines in one year If we only purchased a couple each year, we would have "many generations" in the lab 2) Setting aside a known amount of budget money each year allows us to plan more effectively  3) If we plan 2-year leases, our entire inventory will "trickle down" on a 2-year cycle.  Our lab computers will never be older than four years old, and computers will eventually move fromt he lab to the classrooms.

The reality we face is that we will always have several generations of computers in the building, and that we will use them for 5-7 years at least!  Having more computers of each generation is certainly easier to maintain, and keeps us as up-to-date as possible.