i think they are the performance series Phantom mains (they about 3 feet tall) with the matching center.
a shop here is having a slae and the guy said he would knock a little over $100 off.
normally they go for $450 for the right/left and $200-220 for the center.
i'm sure they'll be better than the speakers that came with my HTIB (especially the center), but will they be THAT much better? everytime it seems i begin to have issues with my set-up, i'll run across an extremely well mastered disc (like U-571 or Superman) and all those issues just dissolve away. it really doesn't seem like there are that many spectacular 5.1 mixes out there.
so is this a deal good enough to jump on anyway, or should i wait & save for considerably better?

That's a fairly reasonable price. The Phantoms are towers with decent extension(but you'd still need your sub) and the center(CC-170??) will blow the hell out of an HTB center.

It will make a profound difference. Especially in bass extension in the center channel. Depending on your corssover(80hz, 90hz, 100hz, whatever), the HTB Center channel may leave a gap in the 80-120hz area which will be properly played by the Paradigm CC. When I got rid of my HTB center channel(actually it was the same as the rear with a slightly wider enclosure) there was lots more punch from the center effects like punches(pardon the pun) and gunshots.

And the Phantoms will give you much more power in the main channels than you had before.

If you decide to get these speakers you can also get some Atoms for use in the rear which should only run you around $175. This will timbre match your entire setup and give a much more cohesive soundfield for panning effects.

$550 is good price, but a not an incredibly great one.

The Paradigm Phantoms are the least expensive towers that I recommend to people. They sound REALLY nice for the price. Not sure which center you're talking about, but Paradigm doesn't make a bad speaker.

What receiver do you got?