It's not too hard to upgrade from that version. It's a two part upgrade process from that version. First, you'd download the 6.5.5 version, and you'd upgrade your current version to that. After that, you'd install version 7.1.1 and then use the available import script to import your data into it.
There is documentation available on the process and we do have upgrade services available if you need help doing the upgrade.
