Problems with USB 2.0 in Win 7 Ultimate 64 bit

I'm running 4 external USB devices plus a second monitor. 3 are from my XP days and 2 of the 3 plug in via AC. The 3rd gets its power via USB. All of their drivers have been updated to be Win 7 compatible. I just bought a second monitor and a second external hard drive which both get power from AC. In XP the first three devices powered on and off with my computer. They do not running WIn 7 nor do the 2 new devices which I recently bought.
Is anyone else having this problem? Any solutions would be appreciated.
I have a Dell XPS 9000 with an i7 920 processor running 12GB of RAM.
Thanks!
Peace!

Maybe they are not pugled in. Open the case and see if they are connected to the motherboard if not connected them.

Thanks for your response but not sure what you mean. All the devices work, but I have to turn them off and off manually except for one which never turns off.
Peace!

Is this the same PC that had windows XP on it or a completely new PC with windows 7 on it? My latest build has an ASUS motherboard in it. This motherboard has an option that will supply power to the onboard USB ports even when the PC is off. If the jumpers are set to supply the aux +5v to the USB ports any USB device connected will not turn off when you power down the PC. Check your motherboard manual if you think your PC might have this option. On my PC it also powers up the PS2 ports so I can turn the PC on by clicking a mouse button or hitting a key on my keyboard.

The USB ports are working as they are transmitting and receiving data. They just won't turn any of my devices off or on when I power up or shut down my machine. This computer has never had XP installed on it. As for opening up the bios, well, I don't really know how to do that. Is this something that Dell should have done before letting the machine out of the factory?
One more piece of info: Not long after getting this machine I ran the first version of Auslogic's Duplicate File Finder on it. A crude utility unlike the new version, but I used it successfully with XP. It found a little over 2,100 duplicate files after the scan (it never found that many on my old XP machine). As in XP I chose to delete them all. According to their tech support they feel I deleted the original files as well. Aside from this USB problem, which started before the scan (actually right out of the box) the machine seems to be in perfect order. It's passing all performance tests in Win 7 perfectly.
Thought that bit of info may be relevant.
Thanks a lot for your help. It's much appreciated. Pklease let me know what you think.
Peace!

On my ASUS motherboard the USB power is set by jumpers not a BIOS setting. When set to +5V they work the way you want yours to work. They are off when the PC is off and any devices connected to them turn off. When set to +5VSB (SB = standby power) They are powered up even when you shut down windows and any USB devices connected would remain powered up. You would have to read though your motherboard manual to confirm you have these jumpers, and then follow the instructions for switching the mode to what you want. It's a hardware setting not a software setting.

That sounds entirely logical to me. It describes my problem to a "T." Unfortunately I didn't get a motherboard manual with my computer and none of the documentation mentions what brand it is. I'll give Dell a call and attempt to find out what motherboard it is and if it has this jumper feature. Perhaps if it does one of their techs can walk me through the process. Thanks tremendously for your help. Very much appreciated.
Peace!

No problem, I poked around the Dell sight trying to get some info on what motherboard might be installed but couldn't find much. If you go to the support section and enter the "Service Tag" number for your PC you should be able to download the manual for it. The service tag number should be on a sticker on your case, its also listed in the BIOS.

I talked to a Dell tech today. The motherboard is one of Dell's. It does not have the jumpers we had hoped. He's looking into it further and will call me back tomorrow. He directed me to the manual section for my computer and a schematic of the motherboard.
Here's the links:
Documentation

Documentation
Again, I appreciate your help!
Peace!

I looked though those links and didn't find anything that might help. I didn't see anything in the BIOS setup that could switch it either. I guess you'll have to wait and see what the Dell representative has to say about it. I think it's a cool option, provided you have the choice of how it's setup.