If your TV has an HDMI port, then get a netbook with HDMI port, and that's it.
Otherwise, get a netbook with both VGA and HDMI output. This way, you can use it just the way you use your laptop, *AND* it'll be future proof. In case you decide to buy a new TV later on (with HDMI port of course), you'll be able to enjoy the advantages of the HDMI connection (it's digital, so better signal quality, and it contains audio, so no need for separate cable).
Little warning: what you cannot do is connecting a HDMI-only netbook to a VGA/RCA port with a cable. They sell cable which is supposed to do this, but it can't work, because there's no way a cable can transform digital signals to analog. http://www.youtube.com/watch?v=w6Vu2gGhzVo
If you want to get a perspective, watch these two videos:http://www.youtube.com/watch?v=pN_yCFttdckhttp://www.youtube.com/watch?v=e0NG7hZSbw4