I looked at your old posts. What don't you like about the mount? As near as I can tell it is an LX200 without the goto or PEC, and you have the superwedge. You can get close to targets with your finder and star-hopping and with autoguiding you can overcome most if not all of PEC. That will get you started before your new scope arrives
Can your laptop run windows software? That makes things somewhat easier due to the huge amount of software for Astrophotography. Um, PHD guiding has an OS X version, but I don't know which drivers it has for guide cameras. Can you run bootcamp or VMWare? I'm a Windows expert, so perhaps someone else can help you with that...
For guiding you can piggyback something like the Orion 80mm short scope (400mm focal length) with an Orion Starshoot Autoguider. This uses guiding software like PHD to drive the CCD port of your mount through the camera itself so you do not need and extra serial port to do this.
I broke my Orion Starshoot Autoguider when I put it with an f3.3 focal reducer on the main LX200 10" and crushed the cable against the fork. Oops. So now I use a Meade DSI II Color camera mounted via f3.3 reducer on a Celestron Omni XLT 127 SCT. My old LX200 Classic does not have pulse guiding so I got a Shoestring GPUSB to control the CCD port. The Omni XLT 127 is piggybacked with a Losmandy V series rail on the top of the OTA with a Losmandy GM 8 saddle plate drilled and tapped and screwed onto the Omni XLT 127s existing mounting rail. This has added about 4kg high off the back, so now I'm going to add a Losmandy weight set to it's underside to balance it in 3D though I have not noticed any increase in drive noise or motor current...
Aperture rules when looking for a guide star. Having the 5" on top is sweet. I use the focal reducer to give me a bigger field of view. Focal length of the guide scope can be very short as PHD guides at sub pixel accuracy so the old rule of long focal length is no longer true.
What sort of camera do you have in mind. Monochrome is obviously best as it is more sensitive and cooled gives you much prettier pictures than un-cooled. The same exposure time as a DSLR for example will give you more detail and brighter images. For this I cannot give you much more info as I don't have one.
DSLRs can give very nice images for the price. I run a 450D and it gives nice images. I like the resolution as it blows up into big prints. You may have noticed a lot of threads on iceinspace lately about the 550D having lots of red noise all over it. It looks terrible... So one to avoid if getting a new one. I don't know which models are good and which are bad.
For a DSLR you will need a #62 T-Adapter 07352 which is a short tube with a 2" threaded ring to attach it in place of your eyepiece holder and t-threads on the back to which you attach a T-Ring specific to your camera. This is a small thin ring with a t-thread in one end and a lens-like connector on the other end so it clicks into the camera like a lens.
There are also drop in t-adapters which go into the eyepiece holder. But, anything which makes the light path smaller can cause vignetting. Ideally you can go to the other extreme and get a 3 1/4" visual back to suit your scope, but this is not necessary until you've got the basics down pat.
Mark.
