What should I get for my first audio system?

I live in a NY apartment, and I would like a good value system that I won't outgrow too soon (or can move to a 2nd system if I become a audiophile). I'm comfortable buying good used equipment.

Limitations:
-thin floors (avoid subwoofer?)
-would like to play all music from a computer (but my iMac is another room)

I've done some research and here is my current understanding:
1) Source:
-best would be a dedicate laptop in the room loaded with Apple Lossless quality music (>600 kbps)
-Next option is the Wadia dock for my iPod
-Finally, Airport express to send music from my iMac desktop

*Seems like buying a used MacBook is the best?

2) System
-The Decco device (DAC/pre-amp/Amp) seems like a good starter system. It puts out 50W, so I'm not sure what are the largest speakers it can support?
-Can I boost this with a power Amp to support bigger speakers?
-Or, I can buy a DAC and get an integrated amp (like the Creek 5350?)

*Seems like $800 for the Decco is the discount start, which I can then upgrade with a power amp, and then replace with a better DAC and pre amp over time?

3) Speakers
-Two people have recommended the Totems Hawks as having a full range without needing a subwoofer (to avoid annoying the neighbors)
-I'm not sure if a 50W Decco amp can support speakers with recommended power of 30-120W? Should I go for the smaller Arro or Sttaf speakers?
-Or, I can put monitors on stands. Would this give me same quality of sound with less sound traveling through floors?

4) Cables
-I have no clue how to pick nor what's a fair price for the value

Current plan:
-Used MacBook ($500)
-Decco device ($800)
-Totem Hawks/Sttaf/Arro ($500-$2000)

I realize that there are tons of questions in here, but I appreciate any help with my simple question: what should i buy?!?!

Thanks.