Update...I just got hold of PearPC 0.1.2 and OSX 10.3 today  
 
 I have a Pentium 4 2.8Ghz, and the emulation is indeed rather slow, but usable.  It takes about five minutes to boot the image.  Moving windows around and minimizing/maximizing lags somewhat as well.  However, I can use it without getting a headache.  

   I found I could speed up Finder a crapload by clicking on that oval-shaped thing in the right-hand corner (lol...what's it called?) so that it looks like the old Finder, and using new windows each time.  There's no networking support for Windows yet, so I can't test out Safari.
But I must say, OSX is quite an amazing package.  It's like the classic OS with an opening to the internals, thanks to the terminal and Activity Monitor.  

   Just one thing...how do I make the Unix hierarchy appear in Finder?  :confused: 
Still, emulating a G3, standard graphics, no USB, etc., I wouldn't recommend any less than my current CPU right now.  

   It's early yet, so PearPC may speed up in the future.