Presentation is extremely important!
I’d say the only instance where presentation was ignored and successful are the illustrators for the Lord of the Rings books. The two brothers (names whom currently escape me) came into the interview with -get this- trash bags full of sketches and art.
Best part? They just dumped the bag onto the desk. The interviewers were stunned, no doubt, but once they caught glimpses of their wonderful work, there was no contest. They got the job.
That’s not how you’re getting the job. In fact, in a lot of cases, you will never meet the person in person. If you do however, have a nice large portfolio (I’d say about 11x17in) to showcase your work. Always have one handy, and if they wish to look at the work longer, offer to come and pick it up later. Sometimes it will give you an upper hand in the decision-making process.I know some people who are showing off their stuff with Ipads now. It’s fine, but you wouldn’t really want to leave your ipad with anyone.
Have a website though. Really. It’s too important nowadays to not. And have your own space, not some portfolio page on deviantArt. It’s really not that expensive to maintain your online presence, and a lot of websites make making websites easy.