Should I get the new Apple TV if I don't have a digital TV?
Solution 1:
I don't think it'll work. According to the Apple TV's tech specs, playing protected content (which I imagine means the one you'll get from iTunes rentals and Netflix) requires HDCP, so using a converter box probably won't work. At least the ones I've found online after doing a quick search specifically say they won't work with HDCP.
Solution 2:
The Apple TV really won't work with any TV that doesn't support high-definition HDMI input capable of displaying 720p 60/50Hz. Additionally, everything will work through a converter unless the converter doesn't support HDCP (most don't). All protected content (which is most video and some music bought through iTunes) will not play through HDMI without HDCP.