Try putting your credit card in your CD/DVD drive or Express Card Slot if you have one. The former swipes the card, whereas the latter reads the chip. Once your Mac has verified the card you will be taken to a special pre-order screen where without even having seen the products you can select from the following options:
1) Pre-order all new products regardless of usefulness
2) Pre-order only useful products
3) Pre-order only cool products
4) Pre-order a lucky dip selection of new products