Keynote: Flowchart Creation?

I need to create a very detailed flowchart and was told that Keynote may be able to help. As I go through keynote it doesn't seem to have the detailed capabilities that I need. My question is is keynote appropriate to use for business flowcharting or is there a better software out there I should purchase/use?

I have an ibook g4 with 1.33 ghz and 768mb memory.

Thanks.