So it does work for the subs! Thanks! This is what is on the cables in my walls. i just now got to take a look, they have HD 59 on them with the words "High Definition" on them instead of the usual RG.
My take, especially for component, is, if you've got one, use it. If you're going to buy, get the RG-6. If you're doing HD-SDI or something like that, use the RG-6. If you're doing SD, then pretty much anything you do is okay with RG-59 - unless, maybe, you're doing really long runs (>200 feet.)
RG59 has a 20 gauge inner conductor, while RG6 has an 18 gauge connector. This ends up translating into a thicker cable overall (.242 vs. .332 inches outside diameter) and less loss on the cable. I believe RG6 has a signal loss of around 7db over 100 feet while RG59 is around 10db over 100 feet.
I also don't believe that the amount of shielding is included in cable specification, rather you can buy RG59 or RG6 with different levels of shielding. I think Belden makes both RG59 and RG6 with about 5 or 6 different types of shielding.
For longer runs - RG6 is generally preferred. However, if you are going short distances and need a flexible cable, a high-quality RG59 may be better (as RG6 is not nearly as flexible).
...though if you really need flexibility, I know Beldin also makes versions of RG-59 (and maybe RG-6) that are stranded. They really are flexible, but they also really limit your options for terminating the cable. (Compression connectors are right-out. A number of crimp connectors are out, too.)