Can I use a G3 iBook instead for....?

[Black Landlord]

You're going to need at least a G3/800 with at least 384 if RAM; you'll find that some sites are very boggy and you have to close other applications to hope to stream video smoothly (you won't always be able to) but it will be surprisingly workeable for the use you describe.
Tiger will run beautifully.
I wouldn't recommend anything less.