Forgive me for asking a very noobie question but i did however

and found nothing that really suited what I needed to know.
Finally got a Lilliput for my xmas to noticed my dad had ordered a 7" VGA non-touchscreen one!
Emailed the guy from ebay but wont reply to me so thats out the window for a swap (havent even opened from the packagaing yet!)
Looked on dww and saw they have touchscreen kits and so on. If i buy the usb cable, is that all i need to buy to add touch screen capability or am i way off the mark?
Also, is there any quality difference between say the cheaper usb version and the more expensive Touch Screen Panel
Thanks.