Personally, I think you should just get a host and host your own forum.

Forum hosts like Invisionfree are not bad, but they have a lot of downsides.

For one, you have to put your site and forum on different websites for most of them.

Also, you can't mod your site (most of the time) with themes, skins, or things like that.

Last, you have to put up with crappy ads all over the place, and follow strict TOS's.

However, if you still want an IPB host, I would go with http://jcink.com/ .

Stick with invision plus, it is the easyest i think. i tired that and i didnt like it to much. invision plus is just simple and easy to use.

A free IPB host, you don't see that often
I started my first forum(s) with these kind of services too, now
I am far enough to set up a forum on a host

Greetzz