Just thought I would chime in, so people trying to make a decision of whether or not to upgrade have more to make a decision with.
I have a Sager 8890, and I just installed and updated to SP2 last night, no problems.
A couple of precautions I did beforehand:
1) Made sure my system was CLEAN. No virus, no spyware, no trojans.
Recommended programs (that I used to ensure this) were AdAware, Spybot Search and Destroy, Hijack This, and Security Task Manager. - Did this step with System Restore TURNED OFF.
2) Uninstalled all popup blockers, antispyware, firewalls (just to be safe--I wanted a CLEAN system, because I'll admit I was nervous about the upgrade)
3) Rebooted to a totally clean system, turned System Restore back ON, then made a clean System Restore point.
4) Installed SP2. No problems.
Yay for me.
Good luck to those of you chewing your nails on this, I understand the feeling.