Front Jack is broken,The back one isn't shown in Audio Prospeties.

Nope,I think it can be fixed inside the Realtek HD Audio Manager,but don't know how

That is the same as my setup. I think the only way I can change this behaviour is my audio driver provided software that has an option for Independent Front Headphones, you could check if your new drivers have installed any application that may have this option.

Where should I seek it from?

You could check the Advanced settings in the top right although I not sure this will be possible.

Nope,has nothing to do with it.

Do us a favour and take a screenshot of the advanced settings.

I've looked at 2 other different images of this dialog and yours is different again. I honestly don't think you will find a solution. You can try Google as I have had a quick search and found a couple of pages with the same problem neither had a solution.

You could try another version of the driver, Fujitsu has a Vista driver, a much earlier version that might have this option but it may not work with Win7 and theres the chance the ALC260 doesn't support this feature. You'll find that driver here Technical Support pages from Fujitsu, just put your serial in the box provided, click continue, select Win Vista and Win Vista again, select Audio and click download on the right.

Otherwise you could live with it and like me (even though I have that option) turn off the speakers or unplug the headphones depending on which one you are using.

Let me know how you go but I have to go now I'll check back tomorrow.

Still haven't found a solution to the second problem..