I agree with Ron. Many German equatorial mounts are heavy, especially one capable of supporting a good size lens and your camera. Add in the mount weight/counter weight and you will far exceed the safe limits of your tripod. Your camera and lens along are about the max for that tripod. Most equatorial mount tripods have 2-3+ inch diameter legs and heavy hardware. Sorry for the bad news Rick but the last thing you want is everything to end up on the ground. Check around at Astromart and see the products there for examples.
Congrats on the iMac. Got one for my wife and I've always been Mac based, great products, fun to use.