Standby is a low-power state in which the computer is still on, and information is held in memory. If the battery runs out, or the power fails, when the system is in standby, everything unsaved will be lost. It consumes much less power to keep a computer in standy than running on full power, and the time taken to resume is comparatively short, so it’s a good compromise.
When you put Windows into hibernate mode, everything in memory is written to disk, and then the computer is turned off - so a computer can stay in hibernate indefinitely, even without power. When you resume from hibernation, all your data is pulled off the disk and put back into memory, so you can resume from the point where you left off, even if you hadn’t saved your data.
On my laptop (Dell Inspiron 510m), there’s a key combination for suspend, but to hibernate I have to go to the Start menu. YMMV.
Well, the original OP seems to have been answered, maybe I can borrow the thread for a minute.
I have XP, SP2 and cannon get my computer to shut off or go into hibernate (or stand by).
When ever I select either of those two options, the computer performs a restart. I have to physically punch the button to actually shut it down. I’ve recently rebuilt the harddrive (reinstalling a new copy of XP) and I don’t remember whether I had the problem before or not.