For graphics tablets, I've tried a few and haven't found anything that beats Wacom's: http://www.wacom.com/en/ca/ (just my opinion)
For screencasting software there's a long list of FOSS and proprietary options: https://en.wikipedia.org/wiki/Comparison_of_screencasting_software All have their pros and cons and it depends on what you want to do. One issue with the proprietary screencasters I've seen is that they only encode to a narrow range of proprietary video formats at high compression rates. If you want to support multiple platform, and therefore CODECs, it's important to save the video as a high bitrate master file and then encode (compress) that down to the various target formats at low bitrates. Here's a good FOSS screencaster to start with: http://freeseer.github.io/about/index.html
If you intend to talk over the demo, get a decent quality microphone and you may need an external sound card (that's shielded from computer CPU and GPU HF noise). Some people like all-in-one USB mics, I prefer a super-cardioid mic (Rode NTG-2) and a separate sound card; more expensive but higher quality, less background noise, also more flexible and ultimately useful, e.g. they're excellent interview (plug it into a PCM WAV recorder) and video camcorder mics. They're also easier to shock-mount, i.e. isolate them from vibrations and handling noise.
BTW, if you intend to do more than occasional screen recording and/or video editing, I recommend NOT using a laptop - They're not designed to do that kind of heavy lifting and can't cool themselves sufficiently (unless it's some kind of gaming laptop). You'll more than likely cook your GPU (It's accumulative over a period of time) which is often more expensive to replace than buy a new laptop. Also a 64-bit OS will work much faster than 32-bit.