xlr8yourmac.com has a big deal of feedback on various G4 systems and upgrades, very interesting als to 2MB G4 CPU upgrade card from MetaBox.
MacWEEK has a whole series of reports and closer looks at OS X. And also some bad news concerning driver support.
SharkyExtreme has a brief presentation of Intel's next gen CPU, the P4. Read it and you'll know all you want to know for comparisons.