Considering buying used mac laptop

[tylerjca]

Hi,
I'm wondering if anyone can help me out there. I'm looking at buying a used mac laptop but I want something decent for a good price. What should I look for? I mainly just want it for web site testing and development but also to get aquainted with the system. I've been on eBay and I've found items such as:

iBook PowerPC G3
500Mhz
192MB
Mac OS 10.4, Tiger

Is this a good system? Or should I aim for something better?
From what I understand, the mac operating system uses much less resources than Windows (any version) so it would require lower resources.. is this true?

What mac specs would be comparable to a Pentium 4 with 2GB DDR Memory?

Thanks in advance

[StupidRalph]

I'm not a Mac person so I have absolutely NO credibility in this but I'm pretty sure that laptop is 3-4 5 years old. I'm also reasonably sure that Mac runs under Unix which many users of this forum (and the cpu world in general) consider to be more efficient than Windows.