interested to do 对做某事感兴趣，想了解某事，interested in doing 对某种想法感兴趣，doing 通常为想法。例如：
I shall be interested to know what happens. 我很想知道发生了什么事。(想了解)
I'm interested in working in Switzerland. Do you have any idea about that?
我对在瑞士工作感兴趣。你想过这事吗? (一种想法)