It's a little over 40 Gb I think but it might be more (it been a while since I installed it). Most of that is either samples for the EXS24 or Apple Loops. That takes a lot of memory.
If you don't have an immediate need for Logic 9, I'd wait. Logic 10 is overdue and should be out soon. That way you'll avoid buying 9 and then having to shell out more for the upgrade.