Well - we had a long discussion about the difference between getting it as a 17.5" or a 20". I eventually decided on a 20" (after having a ride on both sizes), as it felt better, and being 15 years old I thought it would allow me to grow. So, it's ordered, and I'm probably going to wait till Chirstmas to get it - seems fair on my parents as their paying 3/4. Anyway, just like to say thanks to all again.
Richard.