Few options: You can get a 5.1 system that will sound 'very good', and generally blow most people away. Option 2 is you can do a 2.1 system, that while it may not have a true "surround" effect, as far as sound quality goes, it will put any 5.1 system to shame for the same price range. Interesting bit about this though, is that you may find after using a good 2.0/2.1 setup, that you may all the sudden not care much for a surround system anymore.
As far as the 5.1 system goes, bar none, the best bang for your dollar is the Monoprice 10565 system. It is essentially a direct ripoff of the Energy 5.1 Take Classic system, but $100 cheaper, while sounding exactly the same. Combine this with a good receiver like the NR1604, and you got a system that will do amazingly. I recommend the Marantz for it's amazing sound quality, its ability to hold its price better than anything else, and overall higher reliability than most others (cough, Okyo, cough). Trust me, 50watts/channel is MORE than enough for those speakers, and with Marantz, you are actually getting 50+watts/channel, unlike many others.
Personally what I would do though, and what I have been doing for a while now, is running a 2.0/2.1 setup. Tower speakers may take up a bit more space, but are totally worth it. The common misconception people have though is that because they are larger, they require a lot more power. This is simply false, and sometimes completely backwards. In fact, I am currently driving my Infinity P363's off a Lepai LP-2020A+ which realistically is a 15watts/channel amp. Rarely do I even need to push more than 5-10 watts through them to get to some very loud levels. At the same time though, I am sitting at a VERY close proximity to them (3 feet). Distance to the speaker, room acoustics, and the speakers themselves have everything to do with how much power is needed to make them sound loud. Unless you are in a VERY large room (like gymnasium large), getting anything over 50 watts is just overkill.
As far as equipment recommendations go, you could go with a Marantz NR1604. There is one caveat to this though: Only do this if you plan to later expand to a 5.1 system. If you are going to stick to a 2.0/2.1 system, and focus on making that sound as good as possible, then skip the receiver all together! Instead, go for an integrated amp, like the Marantz PM6005. An integrated amp is essentially a simplified receiver, so no HDMI inputs, no multi-functional display, no surround (2.0/2.1 only), no room calibration software, or any of that jazz. Instead, they purely focus on sound. What this means is that they forego those things, in preference to putting that money towards things that make the unit sound better. The PM6005 comes with an optical input so you don't have to worry about getting an external DAC too. The quality is simply...amazing. There are of course other companies that make fantastic products, but IMHO, Marantz takes the cake for getting the most out of your dollar when it comes to sound quality and reliability.
When it comes to speakers, really the sky's the limit. Considering we just spend $700 on a receiver or integrated amp, this leaves us with $300 for speakers. I would recommend spending all $300 on just 2 tower speakers. You could try and tell me all you want on how much you need/want a subwoofer, but let me just tell you that you would be underestimating the bass capabilities of a good set of towers. The little 6.5" drivers on my Infinity's put out enough bass, that everyone who listens to them, including my dad who has a beefy 12" sub in his system, simply can not believe that all the sound is coming out of just 2 tower speakers. DIY projects tend to give you the most for your money if you are inclined (Parts Express TriTrix MTM TL Speaker). Great companies to buy tower speakers from are Klipsch, Energy, Cerwin-Vega, Polk, KEF, BIC, Yamaha, as well as a few others.
EDIT: One more thing about an integrated amp. Technologies change ALL the time. New HDMI standard means new receiver or TV needed. Bluray requiring new software because of DRM or 3d compatibility? New receiver and TV. The beautiful thing about going the integrated amp route is because it is such a simple solution, you could literally use it for the rest of your life, and never have to buy another unit. My dad still uses his Yamaha; I am still currently using his old Marantz 2325 from the 70's. New tech won't make things sound any better as far as the integrated amp goes, so just get a good one, and you will be amazed on how long you may keep the thing.