Most experts agree that you should register your domain for a long time, because search engines factor domain "stability" when looking at your pages. Google and other search engines may penalize websites with domains that are set to expire soon. The reason for this is that many spam sites are often registered for short periods of time.
“After being frustrated with other service providers. Spartan Spark got our website up and linked to a payment system over just a weekend.” -Patricia Marin - Calgary Family Services