I agree with Guy. Buy the best speakers you can afford...for what you want out of the system...and put roughly $700 towards the receiver.
Speakers, if purchased well and thoughtfully, can last well over a decade while receivers generally come and go within 5 years or less as new features/DSP/etc. are introduced.
Before you jump into a system I hope you take the time to listen to and evaluate a variety of receivers and speaker systems before making a purchase.
There are a lot of very good manufacturers out there and you would do yourself a good service by shopping around and buying what you love.
If you have been researching what your money can buy you must realize that using $3300.00 of the budget for a 5.1 system may not get you as much as you expect so shop carefully and regardless of what a salesperson or forum member may advise always buy speakers that sound wonderful to your ears...you are the one that will hear them day in and day out...
Good luck, enjoy the shopping experience and keep us informed.
Do you have a music demo disk? If not I strongly suggest you create one with perhaps 10 of your favorite songs covering a wide genre of music styles that will push speakers in different ways. Too many songs will be confusing to remember differences, etc., too few generally doesn't cover a wide enough mix.
My demos change here and there but currently use artists like Frank Sinatra, Annie Lennox, the Beatles, Celtic Woman, Santana, AC/DC, etc.