I can't say anything about the SoundSticks but the Pro Speakers won't work, as a) they are powered by an amplifier within the Mac they're made for (iMac, G4 Tower etc), and b) the minijack is a proprietary design.
can power Pro Speakers and allow them to get an audio signal from a Mac not equipped with the proprietary Pro Speaker jack and internal amplifier. It gets its audio signal through the computer's USB port. Can't vouch for it personally but I've seen it discussed a lot on various boards with positive comments. I don't know if this device can power both the Pro Speakers and supply the iSub with a bass signal at the same time.
The iSub has its own power supply (e.g. a "brick") and is considered self-powered (as opposed to being powered by the computer as, say, a mouse or keyboard is); it get its bass signal through a Mac's USB port however.
Do you really have your mind set on Pro Speakers & an iSub? Why not look at a Harman Kardon Champagne SE
set? They've got a different kind of cool factor
but they are supposed to be better than a standard Pro Speaker / iSub setup. This particular model is on sale at Future Shop right now, and the price is right around what you'd pay for a new iSub alone. FYI, the FutureShop website has a typo - "Champagnese"
In any case, I've got Pro Speakers & an iSub connected to my iMac and it's a great setup. They won't "rock the house" however they're more than adequate for listening at normal volume, and they are fine for gaming. However there can be issues with the iSub from time to time; it doesn't get recognized by the computer and has to be unplugged & plugged back in. Happens to me once in a blue moon but I can't say it's a major annoyance, really. I think a lot of USB audio devices can get a bit weird sometimes, whether Mac or uh, another platform.