No worries Haarken, Here's an attached piccie:
In order they are: DRM robot/Necron Proxy, a Centaur conversion, Imperial Guard Rough Rider, Baccus Parthian Cataphract and Imperial Guard Standard Bearer.
As you can see, the Baccus rider is about a head taller than the GW one, however the horse is about the right size. Actually, I've just been rooting around and found a pack of Heroics and Ros 6mm Pathan tribesmen (hoping to use them as part of an imperial guard regiment, scouts maybe?) and they look more of a similar size to the GW guardsman. Here's a picture of them:
I think they'll make a nice unit for the Persian/Indian style Guard army that I'm planning.