There's a lot you can do with bigger screens. When their screens become touch screens, there's going to be so much you can do with them. Eventually all TVs are going to be computers with functional browsers, so you better start thinking about fluid design as one of your motivating factors.
Do this. Go to the Apple store and load up your website on one of those really high res iMacs and see how much real estate you have.
I just got a Dell Precision M70 laptop way cheap (around $300) on eBay. It has a resolution of 1920x1200, the largest I've ever seen (in a 15.4" matte screen). What do people consider a 'large' resolution?