I am not familiar with the Axiom line up, but I am familiar with the setup your talking about. At this price point you have a bunch of choices and Axiom is a favorite of many.
First: I have some questions for you:
What is other speakers have you listened too? If you say none, then start listening to others.
You have a large room, and one that COULD take a 7.1 surround system. EXCEPT, very few media support true 7.1 surround sound, and it is easy to balance a 5.1 system around your setup. 2K is a fairly good starting point for speakers. I would invest more into 5 speakers then into 7. You will get a better range of sound, and will fill the room well.
Changing you speaker sellections around a 5 channel setup will probably lead you too a complete set of floor standing speakers. Like I said, I dont know the product line. Given the oportunity, and rememebering that you asked this question on Audioholics, I would recommend you go with floor standing speakers. You have allot of room to place them in, and you wont be unhappy with the extra room the BASS has to develop in the enclosure.
The room wont be full, and so you will be left sitting away from the front speakers. This will be great because it will limit the listening area, and allow you to better focus the speakers for everyone.
If you get floor standing speakers, and find that you have to put them around your furniture, you can always lift a floor standing speaker with the best possible speaker stand available. A Cinderblock.
You will end up with a better sounding experiance. And when the Blue-Ray and HD-DVD world finally sorts out, and if they start offering 7.1 dvd's... THATS when you can go onto Ebay and buy some used speakers to fill the extra channel.
Which brings me to another good point.
BUY USED SPEAKERS!
Lots of people want new equipment, and when it comes to electronics, I almost always say yes... New is better. Then again, I dont specialize in Electronics, I like the price point your talking about. Anyways, back to what I was saying. Used Speakers from a company like Axiom are a GREAT investment, and you can expect about 60% or lower of the original value. I HIGHLY recomend buying used.
There are a few places to buy used, ebay is one of them. You will find yourself with the ability to spend more on higher end equipment.
You got to realize that Axiom and audiophile speakers are a fine engineered peace of equipment, made to withstand its tollerances. If you go past the tollerances, the speakers dont become distorted or drop in quality. They simply stop working.
That means when you buy used, you will have a speaker that performs like a new speaker, or a speaker that has a driver that doesnt work. If this happens replacement drivers are available, and usually you can get them just by showing up at a Axiom dealer.
The down side of used speakers is that they almost always have small dings or scratches.
Just my idea.
Mike