Sean, if it were me, I'd stick with your 130mm OTA. In some ways, the OTA is the *least* important part of the imaging rig. Your 130mm f/5 scope will be just fine to catch a whole lot of nebulae and cluster images if it's on the right mount.
The mount is the *most* important part. You'll want an equatorial mount that is capable of being autoguided. The link Paula gave you is a good one, except that I reckon you could use your existing OTA, just buy the EQ5 (or HEQ5 if you want GOTO) and spend the $400 you save on an autoguider package like this one:
http://www.bintel.com.au/Astrophotog...oductview.aspx