If a laptop breaks once in the first three years of use, and you have 36 laptops, you could have one repair situation every month. Do the math to fit your network. Now, should you be treating broken laptops as emergencies with ad-hoc procedures or as a part of what you are set up to do as part of regular operations?
If it's an emergency, you catch-as-catch-can through the process. However, if you are set up to deal with the situation as a part of doing business, you can justify having a spare laptop, an external USB/Firewire disk (for recovering data), and so on. I point this out because at previous employers, our CFO would not tolerate the purchase of "spare" computers, just spare parts. Though, we didn't have 36 laptops, so in hindsight she was right... sort of.
In my experience, the technical breakage I experience on desktop PCs are fairly rare. They usually involve a hard disk going bad or a keyboard filling up with enough corn-chip crumbs that it stops working. In the first example, good backups are our friend. In the second case, a new keyboard is fairly inexpensive nowadays.
However, rarely have I had a video card suddenly stop working, or a motherboard die. Yes, I've heard it happen to other people, but in general that always seems to be related to someone installing new hardware that conflicts with other hardware and, well, you guys know the drill. (To you Mac owners, have a x86-owning friend explain it to you).
However laptops are different. Laptops seem to be treated like crap by even the daintiest of users. People drop them, slam them, toss them into the trunk of the car before speeding off bouncing it around. That's a lot of wear-and-tear. Even if you have a fancy carrying case, there can never be enough padding in my opinion.
In the last three months I've had to process six broken Mac PowerBook laptops. Two repairs were on my primary laptop, an Apple Powerbook G4 15" which is only a year old. The fact that all these repairs were Mac Powerbooks is less about them being fragile, and more about the fact that so many were bought around the same time.
While on the topic of Mac powerbooks, I need to confess that I used to recommend them because they are metal and look so rugged. Well, I was literally correct, they look rugged, but in reality looks are meant to be decieving. Apple doesn't claim them to be very durrable. Instead, all their durability know-how is expended on their iBook line of laptops, which are designed for students. I'm now only recommending the purchase of iBooks where I work because I'm on a "durability is everything" kick. The iBooks used to be a lot slower and didn't have as many jacks. However, iBooks are now nearly as fast and have Firewire400, USB, and all that good stuff. Plus, their plastic shells absorb impact, instead of transmitting it like a metal case does. But enough about iBooks.
While I tend to not recommend "service contracts" on consumer goods like stereos and VCRs, I have always recommended them for laptop or any computer that is going to be moved a lot.
Apple sells Apple Care Protection Plans (APPs) for their laptops that last 3 years. Dell has something similar. I'm sure other vendors do too. Everyone seems to hover around the 3-year limit. That tells you something: the average laptop, under the usual amount of wear and tear, will be unprofitable to support after 36 months.
That means a lot. Don't expect laptops to last much more than three years.
What that means to people who pay for their own laptops is not just to purchase the 3-year service contract, but also to start saving for their next laptop the day they buy their current one. If you pay $2,000 for your laptop, set your Quicken or automatic bank system to transfer $55 each month into your laptop fund. When the 3-year service contract is up, you are now sitting on a ticking timebomb. Every month your laptop lasts you "win" an extra $55 towards your next laptop (or retirement, or groceries, or weed, or whatever). When your laptop does die, you have the money to replace it.
This is a much better deal that putting the computer on a credit card and paying it off over the three years. Saving $55/month in a INGDirect account paying 3% interest for three years will result in about $2100 to buy your next computer. If you, instead, purchase a computer for $2000 and pay it off at 15% over 3 years, you'll have to pay $68/month (so the monthly payments are higher) and you'll end up paying about $500 in interest. In the first scenerio you paid $55/month and bought $2100 worth of computer, of which you paid only $2000 for. With a credit card, you paid $2509 to buy $2000 worth of computer and had to shell out $68/month for three years.
Which would you rather do?