Nahh go for a very high end Dual G4 - the dual CPU spread works much better with UNIX OSs and load balancing for Apps. Most Dual G4s above 1GHz rip the backside out of low-end G5s anyway.
The only benefits from buying a G5 are the USB 2.0, SATA and FW800, oh and a really cool looking case (that's damned heavy!).
TBH if you want a high performance Mac you shouldn't look at anything single CPU/Core. Only having one CPU core is what causes a lot of OS X stuff to bog down. Multitasking and multithread work goes one hell of a lot faster just by adding a second CPU at the same speed. Tha said I went from a single 800MHz iMac t oa MAc Pro 2.0GHz so the step was more like a leap! I have seen the evidence on lesser machines running other UNIX OSs though.
The only benefits from buying a G5 are the USB 2.0, SATA and FW800, oh and a really cool looking case (that's damned heavy!).
TBH if you want a high performance Mac you shouldn't look at anything single CPU/Core. Only having one CPU core is what causes a lot of OS X stuff to bog down. Multitasking and multithread work goes one hell of a lot faster just by adding a second CPU at the same speed. Tha said I went from a single 800MHz iMac t oa MAc Pro 2.0GHz so the step was more like a leap! I have seen the evidence on lesser machines running other UNIX OSs though.