So i've had various setups working on single and dual core atom netbooks, some using internal soundcard but usually with an external soundcard. My 'portable' unit is now a Win 8.1 tablet, using an iMIc USB sound card, concurrently running 3-4 instances of DSD+ (as I get all flavors of digital mod to decode). It's light, portable, battery lasts for ~12hours and for DMR you can easily see the screen to see what DCC is being used. So if you've got nowhere to plug in, don't forget 2nd hand laptop batteries don't tend to last long.
Personally I would throw some caution on the dongle (vs scanner) view though. Yes a dongle is light and more portable, but the sensitivity is much worse. For me a dongle works fine in a fixed installation with a good antenna. For good decodes you need a good signal, and therefore every bit of sensitivity helps. You'll have to faff about with a dongle's antenna too. I use a tapped Icom R2. If I compare my setup with some of my early analogue scanners, the whole setup is just as portable and not far off the same weight.
HTH
Jim