Surely thats:
IF (SpriteTilePos.x+SpriteTileWidth<0) dont draw
IF (SpriteTilePos.x>OSB.Width) dont draw
IF (SpriteTilePos.y+SpriteTileHeight<0) dont draw
IF (SpriteTilePos.y>OSB.Height) dont draw
?
no RobG thats incorrect - that would clip as soon as the sprite went 1 pixel to the left...