I am considering buying the season pass of LOST - and am debating between HD and standard. What is the difference in how large the files are (approximately)? I hear this season has 18 hour long (42 minute long) episodes. Is HD double the size of standard? And about how big is each? My Apple TV (160GB), Mac Mini Hard Drive (320GB), and ipod touch (32GB) are all getting smaller it seems! Thanks!