Good Morning, Shane!
My name is Jamie, and if you'll allow me I'll try to answer a few of your questions. There are other here on DIYLA that can provide much better answers, but since I am one of the first to see this... you are stuck with me.
I would like to go with the RGB LED strips and nodes.
That means you are going to need something that does DMX or, in the case of equipment here at DLA, pixelnet. As you may, or may not, know pixels use three channels each. One to control the red, one for the green, and one for the blue. If you have a string of pixels that are 100 lights long, then you are going to use 300 channels just for that string!
DMX is an industry standard. Its arranged in "Universes" which consist of 512 channels each. You can have a mixture of standard AC controllers (often called "lightpacks") and DC controllers (that usually control your LEDs, servos, etc). The AC controllers will take care of standard incandescent lights, or pretty much anything using AC power.
Pixelnet is a custom developed protocol developed by RJ here at DLA. It, also, is arranged in "Universes", but they consist of 4096 channels each. It was specifically designed to take care of the issue of needing thousands of channels to control light strings.
I have seen a few programs like Vixen and LOR and light show pro... but would like to keep the price down and use the dmx
Ya see... I just didn't read far enough.. you already know what DMX is. Ok, on to the software.
You've listed the "big 3".
Vixen: Free! - and actively developed. Its not commercial software, but its pretty darn good at handling large amounts of channels.
LOR S3: ~$150 (less if you purchase a controller from them). - Pretty slick software and, through E1.31, handles all the RGB tasks.
LSP: $250-$400 - Not real familiar with this software, but there are many here who use it.
If cost is the issue, then Vixen is your likely candidate. The nice thing is, you can download ANY of them for free, play around with them and then decide which you like best. Choose wisely, because once you get used to an interface it becomes a struggle to change types later. (I'm using LOR's S3 because I started with their controllers... I've tried to learn Vixen, but I have a hard time wrapping my head around it!)
I am confused by how you can piggyback the 9 channel dmx boards to get multiple boards to operate sequensially together!
Each board is assigned a different set of channels, so if you have a few 9 channel boards, the first would be set to channels 1-9, the second 10-18, etc. While they receive ALL the channel info, they will only "listen" to their assigned channels. You can also set separate boards up with the same channels so that you may have them duplicate each other (usually at different locations). Daisy chain them all together (up to 32 controllers in the DMX world) on a single universe and you have a working light show! (well, once you get the songs sequenced, that is)
can I use my current LED lights that I bought at the big box stores? even if they are just a simple on / off commandwith out changing colors?
Yeppers! But as you said, they won't be changing colors. Connect them to a dimmer pack, sequence your song to turn that channel on and "blinky"!!! If you want changing colors you have to go with pixels. Be careful though... Different pixel strings use different voltages. DLA controllers utilize 12V DC for pixels. There are many out there that utilize 5V DC which are good, for example, with LORs DC controller. Either type can be purchased as long as you purchase the appropriate controller.
I hope this helps!
Jamie
