I'm waiting for the moment when Libre Office does something that creates a problem for one of my colleagues! What sorts of formatting issues have you had, Chris? (just as a heads up...)

What's your cpu like on the old Mac? I've got Ubuntu running on a fairly old and underpowered Lenovo laptop and the CPU feels like the only bottleneck I can't fix (I'm mulling over putting an SSD in it to get a bit of extra performance out of it).