1. Use you on-board sound, coax or optical to that new receiver.
2. I would recommend Yamaha
http://www.yamahamusic.com.au/produc...rs/default.asp
I have RX-V1800B, but you can get cheaper models which will do.
3. Bose is crap, sorry. Get the best central speaker, you can afford. Then decent surround speakers. Then rear speakers - spend less, as they work less of all.
95% of sound comes from your central speaker. 4% from surround, 1% from rear.
Spend as much as possible on subwoofer - it is important. Volume of sound comes from it.