if you've got tv-out capabilities on your vid card i'd highly recommend using that.
A few words of advice...use the built-in windows multi-monitor support instead of the driver multi-monitor (n-view on nvidia cards) as it lends itself to watching movies fullscreen on your tv better.
Also i would recommend using a player called
zoom player as it allows you to go fullscreen on you're tv when it looses focus (i.e. you can still do other stuff on your comp, unlike wmp)