Well, thanks for all the input guys, I'm not sure I've solved it, but I have reverted back to the simple approach outline by Andru. This is the default in the NeHe tutorials I've been looking at. I did notice a marked improvement though when I switched to 800x600 16bits, so for now, I'm going to stick with that. I'm basically going to write the guts of my game and then worry about tarting it up after I've gotten it all coded up

Thanks for your help... doubtless I'll be asking more questions