I had the same problem as you, and only in Ubuntu I could get a TV out with scart in colour. For some reasons Windows can't do that. Hoever, I have a Nvidia card so things might be a bit different for you.
Since you have a laptop, check the BIOS of you laptop first and make sure the output format is correct (PAL or NTSC). If that is OK, in Ubuntu you need to edit the file /etc/X11/xorg.conf On every system the file will look different, but if you have a monitor and a TV both should be listed in the file. The "device" section controls how to output the signal to the TV. Mine looks like this:
PLay a little with the options there and read some guides on you to configure dual screen setups with xorg.
Identifier "TV Out"
Option "TVOutFormat" "COMPOSITE" #COMPOSITE or SVIDEO etc
Option "TVStandard" "PAL-G" #or NTSC etc
Option "ConnectedMonitor" "TV"