I think it is more about:

- buying very popular and boring hardware
- buying hardware that the OEM doesn't change every week
- using Microsoft's drivers rather than the OEM's ones
- buying hardware that people on the Windows dev team were probably using wink

In my case I used a series of Dell Latitude D series machines, through XP/Vista/Win7 suspend/hibernate/resume has been absolutely rock solid. I can't remember a time when suspending/hibernating/resuming ever failed.

On the other hand I have seen lots of other people's Windows laptops which didn't hibernate properly. The main problem seemed to be freezing during the hibernate process.

My three Macs have definitely been less reliable in this area. They are/were all rock solid at suspending to sleep and resuming from that. They are far, far more sketchy when it comes to resuming from hibernation. In particular if I have Virtual Box running when the machine hibernates, 25% of the time OSX will fail to resume.
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Remind me to change my signature to something more interesting someday