I emulate and capture everything via a Lenovo Y580 laptop w/ a 2.40GHz Intel Core i7, 8GB of RAM, and a Nvidia GeForce GTX 660M video card. Runs most games great, but capturing certain ones can be problematic. If overheating weren't an issue, I'd have had a Gunblade NY video up months ago.
I think getting an external capture device would take some strain off the laptop, but there aren't any reasonably priced ones out right now that can do 1080p at 60fps except for the new one from Avermedia. Unfortunately, it has a ton of other issues.