Mark,
As long as you have a .net v2 or better / sql server 2005 database instance, you're good to go.
It will help you in the long run if the host offers some sort of mechanism to either initiate a file backup (the base DNN instance that's running on IIS), and a database backup (the actual data that is populating the site), and a way to retore from a previous backup. You just need something to fall back on if you attempt an upgrade and something breaks.
The upside of doing an upgrade is that there are typically lots of bugfixes, mixed with lots of enhancements, that typify a DNN upgrade.
You're so much better server to at least try and stay current with the major upgrade steps with DN\N, rather than sticking with a stable, yet older, version. Easier to host, easier to admin, easier to diagnose if a problem occurs.