TIP: for those affected by 'microcode levels not supported' pink screen at installation (cpu stepping mismatch, tlb bug, etc.)

Here is the solution I have found:

• at installation boot press Shift-o

• type in the kernel advanced option: skipMicrocodeCompatCheck

• to make it permanent after installation type at command line: esxcfg-advcfg -k TRUE skipmicrocodecompatcheck

Works for me on Dell PE SC1435 with dual quad-core AMD Opteron 2350 and ESXi 4.0

Enjoy!