If you look at some of the Blender benchmarks that were posted a while back, you can see that there’s not much performance difference between Macs and PCs as Alltaken said - just remember like with AMD, you can’t compare clock speed directly with Pentiums. One thing I will say is that people spend more time optimizing the PC versions. Some people don’t recommend getting Maya for the Mac because the PC version is optimized much better. If you get software that is optimized for AltiVec like an external renderer then the speed is much better.
You do need at least 1GB Ram and fast hard drives help too like SATA because OS X has good memory management but it uses hard drive space to do it.
The thing I like on my Mac is the video editing. The G5 is especially good for this because it has high bandwidth. You will absolutely need a G5 for video stuff. You can’t even play HD on anything less. My G4 can play 480p but no more.
For gaming, there are fewer titles available than for a PC but for me personally, gaming is not a priority and you can always get a PS2 or 3. A lot of good games are still available though like Doom 3, the Myst games, Lego Star Wars, Tiger Woods PGA, XIII, The Sims 2, Colin Mcrae Rally 2005, Call of Duty, Warcraft, battlefield 1942, Star Wars games, LOTR, Halo, SoF2:double helix, James Bond games etc. OS X made it much easier to port games and general software over.
The only Macs I like in the line up are the Mac Mini and the G5 tower - I really don’t like all-in-ones any more because I like to be able to upgrade the monitor without changing computer. The G5 price was a bit surprising to me:
GeForce 6600 128MB
3 PCI-X slots
for just £1399 - that’s the same as the 1.67GHz G4 powerbook.
As someone said though, the Intel Macs should be out next year and I think given that Apple will eventually stop selling PPC machines, the price will drop considerably - just like Rover cars. That might be the best time to buy a G5 actually. Consumers are stupid that way because as soon as they hear something is discontinued, they assume it’s worthless.
I would probably recommend to get a Mac Mini to tide you over and get you used to the system until the Intels come out but I feel you might be disappointed with the performance of it, especially if you have a fast PC. Plus, I don’t think you should buy the first Intel that comes out so you might have a bit of a wait - maybe a year or so. The first revision models are usually problematic and not all the software will be available.
But, there are rumours that you will be able to run Windows on it and Apple hasn’t denied the possibility of running Windows so that might not be a problem. You might even be able to eventually have a machine to run Windows, Linux and OS X together. Apple already support UFS for Linux but they’d have to support read/write NTFS - just now it’s read-only and read/write MS-DOS.
If you compare a G4 for performance, it’s about the same as a Pentium at 1.25-1.5 times the clock speed. That’s a really rough estimate but in my experience that’s about right. So a 1.67GHz G4 is roughly like a 2.2 GHz Pentium. If you look at this chart:
it gives a rough idea about how to compare Pentium, PPC and AMD. All the processors on each row have roughly the same performance. Again it depends on software though.
On that same site, you can weigh up the 1.67 G4 with a 1.6 P-M for features:
It doesn’t have a benchmark but contrary to their processor list, I think the Pentium-m is faster than the G4. The 1.67GHz G4 laptop will play Doom 3 on medium.
These days, your choice on which platform is more down to software than hardware. The costs to performance on Mac/PC is about the same but on Windows, there is more software available and it is better optimized. Mac laptops are usually lighter and have better battery life though.