Hi Kesomir,
The receivers you're looking at are actually quite good. I don't know where you were looking but the RX-V750 does have more power than the 650 which is why it costs more. However, on your budget you may be putting too much into the receiver and not leaving enough to spend on some good speakers.
The Yamaha RX-V450 would be a better price point, but unfortunately the less powerful Yamaha models are only available in 6 channel rather than 7. For this reason, I'd consider looking at Onkyo, Denon, and Kenwood in the L300 range if you want 7 channels.
Now that would leave you about L700 for speakers. If you will be using this system for 2 channel music quite a bit as well, I'd divide this into L500 for two good bookshelf speakers and a subwoofer, then L200 for the rest.
Go to Richer Sounds with some of your better music CDs and listen to many speakers. As a rule, I'd avoid tower speakers that cost less than L200 a pair, especially if you're planning on getting a subwoofer anyway.
Happy hunting!