I gave this post time to age. Think over your question as if you knew nothing of your project. I can't tell if this is on the tablet, or if you want to add a signature box to your web app or well, you get the idea.
I did check out ivista and they have a raft of tablets. Not sure why that matters. Next time, tell all, tell specifics.
Still want to hear more about the project. Web, PC, tablet app? Or did you want to use some tablet as a signature pad that communicates to your app? That communication is going to be what? WiFi, Bluetooth or other?
I'm unsure what asking for project details would be trolling.