Inexpensive Amp and Speakers

I'm really really new to home audio. I have done some audio stuff in my car, but nothing with home audio. I am currently just using some Cambridge SoundWorks $50 speakers haha, and I really started to notice that the sub and mids sound like crap. I checked out the Zalytron website and was thinking of getting the budget German 2-Way speakers. I would probably order all the parts and materials but put the box together myself to save some money.

Now I need a receiver and I am clueless as to what to get. The only audio place around me is Circuit City and they sell moslty crap, so I can't really demo any receivers and plus they wouldn't have the speakers I am going to use anyway. I looked a little on eBay for new and used equipment but I really didn't know what to look for. I need some suggestions on any kind of amp for around $150. It doesn't need to be anything fancy at all, because I'm ONLY going to be playing music out of my computer, so the amp just has 1 set of RCA inputs and a line-out for a sub it'd be fine. I think that about 100w per channel would be fine, but I'm not really sure how many watts those speakers can handle.

If anyone has any suggestions on other speakers and amps I could look into I'd be very greatful to hear what you have to say. I'm sure almost anything will be better than these cheap speakers I'm using now!