Ralck

Hello, I would like to buy a set of bookshelf stereo speakers to hook up to my computer along with a small pre-amp/amp setup. However, I don't really know much about this. My uncle told me to buy a pre-amp to control volume, hook this up to an amp so if I make it clip, the amp is clipping, not the speakers, and then get a set of good stereo speakers to hook up to the amp.
I also heard that I should be looking at RMS watts, not the watts that are listed, as these can be misleading. However, I don't know much more than that. I'm not looking for very high quality, just enough to produce good sound.
Does anyone have any tips for other features/specs I should look for? What would be good watts/RMS watts that I should be looking for to produce a good volume? Also, what would be some good brands to look into? Price is somewhat of a factor, as I don't want to spend much more than $200 if possible. My uncle suggested I go around to tag sales looking for cheap prices on pre-amps and amps to keep price down. Is this too risky?
A final question, as I have only really dealed with 2.0 computer speakers before this, should I buy a subwoffer and if so, what kind and how big?
Thank you for all your future responses,
Ralck