Hi,
This is my first post here having stumbled across this topic when one of my Google Alerts flagged up "computer leasing". I won't go into a sales pitch (I believe that's frowned upon!) but would just like to put across a few general points about the advantages AND disadvantages of schools leasing their equipment - hopefully I won't come across as too biased!
Leasing certainly can be cost effective, but it depends on your circumstances. If you have a rolling replacement scheme of 3 years, and don't want to own the kit at the end of that timeframe, there's a good chance leasing is worth taking a look at. Leasing can help a school get more out of their budget and it offers predictable cash flow for the duration of the lease. Leases will usually include the cost of any disposal too, so it's worth considering that cost in a lease v. purchase decision, as it can be overlooked. By leasing kit over 3 years it often ties in with manufacturer's warranties too, and if you do adhere to a rolling refresh then you should find maintenance costs come down because kit always stays in warranty.
However, leasing isn't the be-all and end-all (unfortunately for us!). If you like to own the equipment, then you should never really lease. If you like your equipment to have lifecycle of over 4 years, then again, leasing is probably best avoided (with the exception of leasing servers, perhaps).
One important thing I should mention is that LEA-backed schools do have some strict rules to follow when leasing. LEAs will insist that the leases are Residual Value Leases. This means that the leasing company must take an equity stake (residual value) in the equipment so that the school does not lease against the full cost of the equipment - rather the cost minus the leasing company's equity stake. The leasing company then aims to recoup this stake at the end of the lease, usually by selling the equipment to the second-user market. The specific rules on this subject are interpreted differently from LEA to LEA however, so it's always best to consult with them first.
I've probably missed out something, but if you have any questions please feel free to ask and I'll do my best to give you some honest answers.