Ah, thanks for that - and indeed that will work, but I deliberately want (and need) to render to a texture.
Back story:- I've already got all the textures I need for this project (there's a LOT of them) but they're geared up for a full-screen program. What I want to do is draw to a full-sized (hidden) texture, and then copy that texture to the screen - reducing its size as I do so.
I hope that makes sense... it's 01:30 here and I'm past tired!!