the only video cards i've ever seen able to output clean tv signal (on a single rca connector) through the vga port are some old matrox millenium AGP cards (g400 and g500 series).
Since then i've tried a lot of other various (newer) video cards and i haven't been able to get a tv image out of the vga port, but these usually have an S-Video port, so that's not an issue with them.
If you really need a tv display from the vga port i suggest you get a vga to tv converter box, it's a bit more expensive (around $20...$25 on eBay, shipping included) but you don't have to worry about the laptop not being able to output a tv signal through the vga port.
One word of advice though: avoid those converters that support only conversion from 640x480. Look for at least 800x600 and 1024x768 if possible..