Desktop vs. Laptop computers

I realize thread might get more heated than a Bush/Kerry thread, but I thought I'd ask anyway.

I'm being asked by some friends who have an office for their business. It is only the three of them and they're seeking to replace some computers. Two have laptops, one has a desktop. The two have laptops because 'it's cool' and they cn take their work to a local coffeeshop (or home)* and do it. The problem is, their laptops are falling apart after a few years.

I'm planning on recommending desktops for them, if only because they tend to last longer (they don't necessarily need the latest/greatest hardware or upgrades).

My question is,* how long of a life can people expect (generally) from a laptop vs a desktop? I am ball-parking laptops as two-three years, depending on wear and tear, and desktops being six or seven. Does this sound right?

Does anyone have any insights as to why my recommendation might be right or wrong?