GrimFusion
... I don't suggest buying any kind of laptop for gaming unless you make enough money to
buy a new laptop every three to four years to keep up with brand new game releases. With a desktop, the power supply and graphics card can be swapped out and upgraded every few years. Assuming you aren't buying the best and newest-to-market beastly graphics card but settle for something a little more middle-of-the-road but capable, upgrading a desktop would be more cost effective in the long run.
Let's be realistic here. With the exception of people could be equally well served by a netbook, any laptop you buy for nearly any purpose will probably need to be replaced every 3-4 years anyways. That's not something that's exclusive to gaming laptops.
If you compare a 5 year old laptop to what is available today, it's basically a larger, heavier, more power-hungry, shorter battery life version of a $400 netbook. It's relatively rare to see 5 year old laptops out in the wild, many of them simply aren't rugged enough to last that long. As they grow older, they also get more expensive to repair as they fall out of warranty and certain parts become scarce.
Any laptop that you buy intending to use for more than just Internet will be approaching obsolescence after 4 years, assuming it even holds it together that long.
I do know people using 5, 6, or even 10+ year old laptops, but in all those cases one or both of the following is true.
1) It's not their primary computer. They have easy access to another more powerful/recent computer.
2) They are too poor to afford even a netbook so they're making due with what they've got.
Desktops tend to last longer and lose value more slowly, in large part because they aren't subjected to as much physical abuse and they are easier/cheaper to repair/upgrade.