My friends say its more beneficial for me to buy the 602 because of the larger mid-range driver and that I will save about $500 CDN which will be put towards the sub-woofer (which they say is much better than the passive/radiation speaker on the 603).
Look, with either speaker you will want a subwoofer for surround sound. In your size room either speaker will put out adequate bass and dynamics for music. You will NOT save $500 going with the bookshelf speakers because you have to figure in the cost of good quality speaker stands.

If you were choosing between the 602 and the 602.5, I would say go with the 602. But the 603 is a good tower speaker for the money (BTW, that's a real woofer in there, not a passive radiator. Look up the definition of a 2.5-way speaker). You should choose based upon which you think sounds better. From what I'm reading here it doesn't sound like your friends know too much about home audio.

P.S. Go with the Rotel receiver.