When you pressed the sleep button, but the fans and such stayed on, 3 things could have happened:
1.) The computer went into S1 (this is like S3, only with the fans on and it consumes almost as much power as running).
2.) The computer went into Away Mode (was there a recording going on, or had you started to record live TV?).
3.) The computer tried to go to sleep, but couldn't because some driver is preventing sleep from completing.
Here's how to work around each of these issues.
1.) You don't want to use S1--it consumes probably 50-60W on most machines and the fans and HDDs are left on. You can check to see if the computer is using S1 using the inbox "PowerCfg.exe" tool. To see which sleep states are available, run:
C:\>powercfg.exe /a
The following sleep states are available on this system: Standby ( S3 ) Hibernat
e Hybrid Sleep
The following sleep states are not available on this system:
Standby (S1)
The system firmware does not support this standby state.
Standby (S2)
The system firmware does not support this standby state.
C:\>
The key is to make sure that in the first list ("following sleep states are available"), S3 is listed. It's OK if both S1 and S3 are there, but not OK if it's only S1. If only S1 is avaialble, go into BIOS and switch it to S3 or S1/S3.
As long as S3 is available, Windows will not go into S1 when you try to put the machine to sleep.
2.) By deafult, Vista will go into Away Mode when you press the sleep button if there is a recording in progress and the computer is on AC power. This happens because there isn't a way for media center to prevent the sleep transition when you press the sleep button, like it could in XP. So, media center enables away mode when there is a recording, and your computer will look like it went to sleep, but it'll really still be running--fans, CPU, HDD, everyhing--it'll all be on except video will be blanked and audio muted.
If you don't ever want Away Mode, you can disable it using these instructions. But, I think you'll want the default behavior, especially because this allows the machine to stay on when you press the sleep button, but a recording is in progress.
To allow/disallow Away Mode system-wide, use these PowerCfg commands:
Allow Away Mode on AC power:
powercfg -setacvalueindex SCHEME_CURRENT SUB_SLEEP 25dfa149-5dd1-4736-b5ab-e8a37b5b8187 1
powercfg -setactive SCHEME_CURRENT
Disallow Away Mode on AC power:
powercfg -setacvalueindex SCHEME_CURRENT SUB_SLEEP 25dfa149-5dd1-4736-b5ab-e8a37b5b8187 0
powercfg -setactive SCHEME_CURRENT
Keep in mind that if you change these settings, they only change for the currently active power plan (e.g., "Balanced" or "High Performance" (SCHEME_CURRENT maps to the currently active plan). Also, if you disallow away mode, it can not ever be used, even if an application such as media center or media sharing requests it. When you press the sleep button, the machine will go to sleep, regardless of if there is a recording going on at the time.
3.) There are still some issues with drivers. The old advice is still good: get the latest BIOS, video and tuner drivers for your machine. You can also try disabling Hybrid Sleep and seeing if you have better success. Also, if your machine hangs on the way to sleep or resuming, you can let it sit for ~10 minutes in that state and it may bluescreen. Then, when you restart the system you should get the prompt to upload data to Microsoft, and there may be a response with an updated driver.
Hope that helps,
