from http://www.intel.com/consumer/products/technology/wirelessdisplay.htm works on some (WiDi enabled) laptops. That might be a selection criterion for your next one.
http://www.amazon.com/Aitech-Pro-Wireless-Converter-06-078-001-08/dp/B000BD68KM seems to work with all laptops.
Is there software/hardware available to wirelessly display a computer's desktop with a television? I have a Samsung LCD TV that is hooked up to my home network, and don't really want to hook up a laptop directly to the TV.