As I recently switched from Virtual PC to VMWare Workstation I wanted to upgrade my VMs to be able to use all cores I have and I granted. Machines I’m using most are Windows XPs and Windows 7. As the Windows 7 migration failed and I’m still about to install fresh W7 RTM, the challenge was XP.
Couple of hints I found on internet and as replies to my question in mailing list but nothing was working or it was screwing the system. But then I found a great document, with the manual, forced, way of switching. Although the document recommends doing the surgery in safe mode, I did it in live system (vivat snapshots) once, with just raw copy (+overwrite) and it worked.
copy C:\WindowsServicePackFilesi386halmacpi.dll C:\Windowssystem32HAL.DLL copy C:\WindowsServicePackFilesi386ntkrnlmp.exe C:\Windowssystem32ntoskrnl.exe copy C:\WindowsServicePackFilesi386ntkrpamp.exe C:\Windowssystem32ntkrnlpa.exe
Anyway, on real important system I would recommend safe mode too. After reboot the system detected new hardware, installed it and after another reboot I was ready to make the cores screaming.