Source: http://lifehacker.com/5950321/when-buying-two-computers-is-cheaper-than-buying-one
You can buy some pretty powerful laptops these days, and a lot of people are quick to take advantage of beasts like the MacBook Pro or big gaming laptops like the ASUS G55VW. However, what you might not realize is that it could be cheaper to get a powerful desktop and a more portable laptop. Here's why.
You might want a powerful computer for any number of reasons. Perhaps you need to do a lot of heavy photo or video editing, or maybe you're a hardcore gamer, looking for the best possible performance you can get. Most people decide they need a powerful computer, then go for a 15" MacBook Pro or other hefty, 15" laptop with a fast processor and beefy graphics card. If you need that power on-the-go, this is obviously your only choice—but a lot of people only really use that power when they're home, so why not buy a desktop and a laptop instead?
Let's look at the math for a second. The ASUS G55VW—the absolute cheapest of ASUS' Republic of Gamers line (pictured right)—costs about $1200 on Newegg. You could build a comparable, if not more powerful, desktop for about $600, and use a similarly-powered laptop, sans graphics card, for less than $500. Not only do you save $100, but your laptop is much more portable, and you get the configurability and upgradability of a desktop.
It's a bit different on the Mac side of things. 15" MacBook Pros start at $1800, whereas an iMac and MacBook Air combo starts at about $2200. However, as soon as you get into more powerful MacBook Pros, the iMac/MacBook Air combo starts to become cheaper, and the iMac is still just about as powerful as the laptop you would have gotten (and has a much bigger screen). Replace the iMac with a Hackintosh—which is easier than ever to do—and you'll save loads, while still getting that killer Mac hardware on-the-go.
Does it work out this way every time? Of course not. Especially when you're looking at Windows PCs, prices and power fluctuate so much across the board that it's impossible to make a sweeping generalization like that. But if you're in the market for a new computer, it's worth looking into the cost of a desktop/laptop setup. Unless you're editing or gaming on-the-go, you'll probably be a lot happier with a more powerful computer at home, and a more portable computer for travel, especially if you pocket a few extra bucks doing so.