An overall budget would be nice but I'll toss out a few ideas. Start with the speakers and then select a receiver that will support them and gives you the features that you want. If you're in a house and money is tight I'd start with the best 2.1 or 3.1 system system (speakers and sub) that I could afford and add the other pieces later based on an overall plan.
The cheapest good solution is 2 pair of Behringer B2030 bookshelf studio monitors ($140/pr shipped). They are somewhat homely and benefit from some easy and inexpensive DIY mods that WmAX developed. You'll have to do a search to find them. Pair them with a
Hsu STF-2 (assuming there is nobody under you). Later you can add more pairs to create a 5.1 or 7.1 system.
Or you could go with a pair of Infinity Primus P362 towers (~$200ea), the matching PC350, and when money allows the matching bookshelves for surrounds. The Primus are super easy for any receiver to drive. Finally add an STF-2 when money allows.
A third option would be just to buy a 5.1 package deal from SVSounds. I haven't heard their speakers but they have a good rep on here and their subs rock.
For the receiver I'd skip the Sony and look at the Onkyo but wait until you choose speakers and see what they require. In the meantime keep your eyes open because at least once in the last month Onkyo's TX-SR608 has gone on sale for under $400. Or if you're in the US and don't need 3D support you can still pick up refurbs of last years 607 for $300 at Accessories for less.