I have done some software translation and there are couple of ways you can go about learning UI-related language. The first thing is to start using applications (including your operating system) in Chinese. This would be the first step if you're serious about this, because otherwise it's hard to get a good grasp of the really common words
Note that words are used differently on the Mainland, Taiwan, Hong Kong and so on. Even simple words like "save" or "paste" can be different, so it's not just a matter of simplified and traditional Chinese. Sometimes it even differs between applications.
There are two good resources you can use:
- 電腦名詞譯名 - This is a huge list of computer-related words. It's extremely useful since it includes both Taiwan and Mainland usage so you can compare and choose the appropriate terms. This list is REALLY big, by the way, by far the most comprehensive resources I've found.
- 有道 - This is an online dictionary that also has a lot of translated articles (parallel texts). This is very good if you want to know how dialogues in programs are written, including error messages and prompts of different kinds. Searching here will take you very far, but do make sure to check examples to make sure the answer you find really is the right one.
I'm not sure if this answer is too "advanced". If you're just looking for the 100 most common computer-related words, others have provided or will provide better answers. This is the best I can offer if you want to go beyond that, though.