I do plenty of things on my Mac Mini that Steve wouldn't approve of.

Modern Mac Minis also come with HDMI ports and older ones can be converted to HDMI with a passive adapter. The only problem with Mac Mini vs that Dell box is that the Mac Mini actually holds value. You won't find one for $140.

I've recently be playing around with a Sony Google TV (NSZ-GS7). If you have your photos in Picasa Web, it's about as seamless as can be. It even syncs your friend's photos, so if they come over and want to show you a slide show, there's no setup necessary. The other aspects of Google TV could use some work, but the Gallery app is seriously good (if you live in Google's cloud).