I have a couple thoughts here, so bear w/ me.
First of all, most people who buy laptops don't really move them enough to warrant spending the extra money (smaller components cost more to give you equivalent specs to a desktop, like you said). Unless you're going to move it around a lot, need to use it on the go, are going to take advantage of free public wi-fi, etc. then the laptop is not going to benefit you much. No offense, but taking your laptop to bed w/ you isn't so much a need for mobility, it's just kind of laziness and not wanting to walk from the desk to bed. Also, keep in mind, that laptops are more prone to problems. If you use it on battery power a lot, then you'll have to replace the battery within about a year, which costs around $100. Also, if you leave the laptop plugged in all the time, that also ruins the battery. Another problem with laptops is that in time, the fans seem to go out fairly often, and then you either need to fix that (expensive repair) or risk overheating the system, which could cause a lot of damage.
My second thought is that I think you are better off having a separate system for gaming. I think you're much better served with a platform gamestation, like an X-Box or Playstation. More stable, less corruption. However, if you're in love w/ computer gaming, I would recommend a separate computer that you can devote specifically to gaming.
Another idea is that I think a really good way to do it is to have both a desktop and a laptop. You can use the desktop for your more high powered operations (games, photos, music downloads, videos) and have that kind of be your master system. Then you can utilize a laptop for mobile internet and word processing. This way you can buy a basic, low-featured laptop (or just reformat and use your old one) and have mobility as an option, but then you've got your good system in place for those activities you do at the computer from home.
You get these people that decide they need to be mobile so they buy a laptop, but they're really just want that option "just in case." People commonly buy a laptop and then want an external wireless keyboard and mouse, external speakers, a docking station, an external monitor, a cooling pad for it to sit on, and a USB hub, so that they can support all these external devices. If you go through the hassle of hooking all this up, you'll have just as much of a cable mess as a desktop anyway. And you won't want to move the laptop b/c then you'll have to hook all that other stuff up again.
Just some things to consider.