D630 headphone noise

Hi,

About a month ago I purchased a D630 which came preinstalled with Windows XP and have been enjoying it ever since.

Yesterday, I bought new earphones and connected the to the headphone jack and I noticed there was a weird low-volume noise in the background, which occurs only when I use the touchpad/pointing-stick.

I tried connecting a USB mouse, and it didn't make any noise (when I use the touchpad/pointing-stick when the USB mouse is connected there's still noise).

I tried my old earphones again and I noticed the noise was there too (I probably never noticed it beacuse I barely used the headphones before).
And I also tried the new earphones with other devices and they were perfect.

When there's nothing connected to the headphone jack there is no noise from the speakers (at least none that I can hear).

I tried installing these new drivers:

- Audio driver - Sigmatel - STAC 92XX C-Major HD Audio - 5.10.0.5515 R171789
- Touchpad and Pointing Stick - R165804
- Intel (R) Wireless WiFi Link 4965AGN 11.5.0.0 (TIC148234) - Intel_multi-device_A13_R171131
- Dell Wireless 360 Module with Bluetooth 2.0 + EDR V4.41.02(D) A00 - R167661
 
I'm dual-booting with Ubuntu 8.04, so I've gave it a try and there was no noise.

How can I fix it?