Hmm, your PCs sounds like they should not have a problem. You might want to check over in the PC forum, or even another ACER projector forum. It's been two years since I used a PC to drive my projectors, and it was not a pleasant experience--just too many glitches. I think your best opportunity to see 3D is with a bluray player in your PC and PowerDVD software or similar, and a 3D bluray movie. That said for the Stereoscopic Player software to work and 3D games (I'm assuming that is where your are headed), you need to force the ATI 5770 to send out frame sequential 3D--so the software needs to do this. Do not select Side-by-Side, top/bottom, field-sequential (interlaced), or checkerboard DLP(which is used by some LCDs). "3D ready" projectors only support frame sequential--sending an image to each eye in 60hz or two images in 120hz--why they need to be set to 120hz. Also, do not confuse with frame-packing, which is what the bluray does--sends two stacked images in one frame. You also might have to select something at the ATI driver level--and for some computers, even do a registry hack (I had to). The projector needs to be set to 3D mode in the IMAGE menu--Turn 3D on and select: DLPlink (not nvidia vision) through the menu. It does not automatically go into this mode even if the PC is sending a 3D signal. The screen will suddenly get whiter and lose contrast. This is due to the DLPlink sync signal being sent to work the shutters on the glasses. If you get inverted 3D--left eye/right eye is switched, then select 3D sync invert. The ATI 5770 does support 3D with the proper drivers, so it should work. You're probably in the wrong forum for help, though--go to one of the projector or PC forums for more help. Good luck. You can turn your projector into one that can handle all 3D formats by getting a 3DXL box or similar (check out Amazon), if you want to stop using your PC and hook up an external playstation, 3D bluray, 3D cable box, media streamer, etc.
Also, frame sequential is the same a page-flipping. And also force your software to output 720p (1280x720)--yes your projector is 1280x800, but don't worry, the projector knows how to handle 720p. You might have to select this at the ATI driver level--think of your projector as you would your PC monitor and set the monitor resolution as you would normally--right click the mouse-select change resolution or go into you AMD control panel--and make sure you have the latest AMD drivers. The projector can handle 1080p, but will have to rescale it, and the 3D might not work properly.