Got my Galaxy W last week on O2 and it came with Gingerbread 2.3.5.
I downloaded and installed Kies ver 188.8.131.5212_41 on my laptop.
It took me three attempts to successfully upgrade to 2.3.6.
The first attempt failed due to the phone not being fully charged, the second failed due to the phone not reconnecting with the laptop and the third attempt worked perfectly and my phone is operating as it should.
I have used Keis to transfer contacts list, photos and videos without any problems so far.