Sorry Carl, I shoulda posted that.
I did notice that the philips stuff doesn't have the same long slots in it that make the RC-1 more flexible - they want you to contact them for specs, I didn't do that yet.
If you can find an Auralex dealer close, their RC-8 is nearly identical in every way to the original RC-1 by USG - this is the stuff that 99.9% of all tested wall designs that have RC in them were tested with. The auralex guy today said most of their dealers charge around $130 for a box of 24, 8 foot pieces - works out to about $.67 per foot. I know this sounds steep, but this is a niche market. Basic economics apply here.
If you want a better wall by about 8 dB, for higher cost you could use the RSIC-1 isolators in combination with "hat" track - the clips cost around $5 each, need to be on 48" centers or tighter, and that's not including the cost of the track. Not sure yet what that runs. Should run altogether around 3 times what the RC-8 would cost, but 8 dB is quite an improvement if it's worth it to you. Here's their site
http://www.pac-intl.com/rc_update_12-02.html
If you scroll down near the bottom of that page, you'll find a comparison chart between the newer RC and the RSIC clip system - I'm pretty sure, though, that they're comparing to the LESS effective, newer version of RC by that company - read the article, and the chart doesn't say WHICH RC they compared to. It also doesn't say what kind and how many layers of wallboard, or anything else that would give it an air of respectability.
Personally, if given the choice at this moment in time I'd go with the Auralex. I think the REAL performance improvement of RSIC's might be as little as 3-4 dB over the Auralex, and here's the cost comparison:
RC-8, $.67/foot, 7 rows (16" apart), 10 x 12 x 8 foot room (just for comparison, no I would NOT purposely build this) 44 feet per row, 7 rows, 308 feet, figure 320 feet - $214.40 and you're ready for wallboard.
RSIC-1 - same room, walls only, 24" centers both ways, 48" except at periphery, takes about 84 RSIC's at $5 a pop, for $420 - now you need 5 rows of hat channel 44 feet long, or 220 feet - haven't priced this yet, but probably around $.60 per foot or another $132, for a total of $552 before you can add wallboard. To contrast this, it would take 11-12 sheets of drywall for an entire extra layer, at $5.50 per sheet or $66 - (sorry, British members, I'm really NOT trying to make you feel bad -

)
OK, this is all hypothetical in that I didn't figure ceiling, fasteners, paint, etc, but you would need all those in either case. It still looks like over $300 more for using the RSIC clip setup on the walls of our 10 x 12 x 8 room.
It's been postulated that most of the added STC from RSIC clips is just because of the extra air space depth - the hat channel is 7/8", the RSIC's stand off about 1/2" more, so you gain almost an inch of air space over RC. I'd probably frame with 2x6's for an additional 2" of air instead, at a cost of about $30 before I'd go for the RSIC's - Just my own feeling on this.
OK, 'nuff ranting for now... Steve