First of all, do a backup. I mean it.
Some changes can ruin your week-end, evening party, social life, etc.

After reading a few hours, having some discussions with my girlfriend about not doing the dishes and the clothes, mister google came with the solution below.

First, I have patched tcpip.sys using a bat downloaded from softpedia. That was really wrong, causing a nice BSOD.
Luckily, it made a backup of the file so I could restore it with ease.

After a few minutes I have read from this site about this command:
netsh interface tcp set global autotuninglevel=highlyrestricted
reboot

To be sure I have changed the settings to “Disable Receive Window Auto-Tuning Level on TCP/IP“:
netsh int tcp set global autotuninglevel=disable
reboot

I got my speed doubled with this.

I’m too bored today to copy/paste the explanation from these pages.
So, please read the above link and do backups before applying any patches.
Enjoy.

I forgot to mention that I have installed Vista Enterprise on the notebook.