Cart before the horse or horse before the cart?


So, I'm finally building my first home theater and just purchased the TV, (LG PK950)so far very happy with my purchase.

My question is, if you were going to be starting with nothing, would you buy your receiver first based on your needs and then the speakers, or would you buy the speakers first and buy your receiver that best compliments your speakers? I've read so much about different receivers better suited for different speakers.

I'm undecided on speakers at this point, but I know I'm going to be buying used, betting I can get better quality for my money.

Paradigm Studio 20's or 40's
PSB GB1
Usher S-520
Energy RC10
B&W 6 series, etc.

Reciever: Not sure at this point, Onkyo, NAD, Marantz, Denon...

Honestly, there are so many opinions and when I think I've got it figured out something else comes up...need a little help please.

Budget:
speakers $500-$600 (used bookshelves)
receiver $700 max

For now, just the two bookshelves and receiver.

System dedicated to mostly HT and some music, IPOD and vinyl, punk and garage.

What do I purchase first? Thanks everyone.
dufrain
What do you currently own?

Personally, I would suggest getting the least expensive receiver that you can that includes pre-out for all channels. This will give you the option to combine it with a dedicated 2 channel amplifier in the future for the best music listening. I think "requirement" might put you in the $800 range for a new item. Speakers don't get dated when it comes to technology, but receivers can. You want one that will handle all of the lossless blu-ray audio formats and HDMI 1.4 that will do 3D TV just to be current with technology.

You'll want to plan for a subwoofer to make a 2.1 home theater for the best sound.
Something similar to a Pioneer VSX-1120-K would be a great unit as it's very current with the latest technology.
I don't currently own a receiver or speakers...recently moved to another city and now am starting from scratch. I've been looking at the Onkyo line of receivers, 608, 707, and 806...haven't thought of pioneer I'll have to check them out, Thank you.

So, it sounds to me like I should purchase the receiver first based on my current and future needs?