This is a little tip taken from the book Vista Performance and Tuning Guide.

They say to put your computer to Sleep instead of hibernating or turning it off each time you want to shut down your computer. I can confirm this – it works wonderfully. Back before I knew anything about computers (and when computers took a year to boot) I would turn my computer completely off. Stupid, I know. But some people actually still do this. I used to always complain because it took so long to get back into the computer. Well, then I grew up and started to use the nifty “hibernate” feature. This worked wonderfully for several years. Of course, Sleep was available at the time, but the word “hibernate” sounded so much cooler. Needless to say (even though I’m saying it), I chose to “hibernate.”

Time passed by and I bought a Vista. Now, I was scared to buy Vista. I’ve heard so many bad things about it. Mostly from gossip which has been proved wrong. I actually like Vista. I’d say go buy Vista, but Windows 7 is out, so go get Windows 7.

The moral of the story, use Sleep on Vista because “hibernate” and shut-downs are too slow.