If you do use ISBoxer (and I can tell you it is the most complete solution I've used), there is still at least one bug and some caveats you'll need to understand with multiple-PC setups.

See this forum for more info. http://isboxer.com/forum/viewforum.php?f=36

There are a few of us that use ISBoxer on multi-PC setups, though not many from what I can tell. Holler and we will at least be able to point you in the right direction.

[edit] I do use ISB for broadcasting my ranger AoE's (ground-targeted) in Rift and it does work fairly well.