Just for help to those wanting to update to 10.6.3
1. Open finder and delete sleepenabler.kext in S/L/E
2. Repair permissions
3. Update using Software update=DO NOT ALLOW REBOOT at this point-I will explain why below
4. Navigate to S/L/E and again see if sleepenabler.kext is really removed-I did not check again and hence had kp-but I was absolutely certain I had removed it
5. Reboot-at this point-bam! I got a KP-and when I booted in safe mode (-v -x flags at boot)-it gave me the message of kernel mismatch of AppleCPUpm blah blah and kext backtrace to sleepenabler.kext
6. I am not good at terminal-so-if you are, at this point you can boot off the retail SL install DVD and delete that offending kext from S/L/E and then repair permissions and reboot and then reinstall the modified slepenabler.kext (G is your friend)-if not- you have 2 choices-learn it-or I hope you have a dual-boot set-up, so you can get into windows and then using MacDrive-delete that kext from under Windows-this was what I did.
7. Reboot now into SL-works! and then first thing I did was kexthelp the new sleepenabler.kext meant for 10.6.3 and repair permissions and then reboot-and all was well for me-I did not have any problem with sound or display and everything appears to be zipping along including sleep.
My sincere thanks to the fine folks who are hosting this site, and also the geniuses at MacyourPC and InsanelyMac web forums without which I would not have had a window into the world of mac!
Machine:Inspiron 1525 Vista Business-SL-Ubuntu triple boot (my toy)