Question for the VURD: indexing and archiving

Here at work, I've been tasked with creating something of a searchable database of content, specifically for proposals. Here's the situation: We write these proposals, in which we answer questions and frequently compose brilliant responses. A few weeks or months later, we receive another proposal that asks a similar question or requires a similar solution/response. We wrack our brains, trying to remember that brilliant thing we said. What was it? Where was it? There's gotta be a bette way.

What sorts of indexing/archiving tools do you think are best, or at least pretty darn good? I need something that'll be *compatible* with Windows to a certain degree. Content searching, etc. Please and thank you. :)