The higher res capable cables really don't help much. The thing only goes to 480p, which really isn't a big deal. On a 60" DLP in the house we rent here at the beach, it still looks great just feeding composite, strangely enough. I honestly wouldn't waste your money on anything more.
If you get MarioKart, don't forget it only comes with one wheel. I find it highly annoying trying to drive all Wii games, but they're even worse if you're just trying to hold a Wiimote up in the air by itself. Get a second wheel. They're just a cheap hunk of plastic.
I'd tell you to enjoy it, but you obviously already are.
Oh, and you can already "stream photos" by just putting them on a web service that has a slideshow mode and then use the web browser the thing has built in to do that if you want. Just a thought. The browser works fairly decent for watching YouTube videos, too. Though blowing up a YouTube video to 60" or more is a recipe for bad video quality no matter how you do it.
--Donnie