I believe you'll find everything here:
Code:
http://allyours.virginmedia.com/websales/product.do?id=11029
The VIP 50 is just as the VIP 20, except for 50Mb replacing the 20Mb. The VIP 50 is £8 more than the VIP 20.
Also, as of today, you get the SKy Premium HD channels with the VIP 50:
Code:
http://community.virginmedia.com/t5/TV/Changes-to-our-VIP-50-Bundle-from-5th-August-2010/m-p/107310
The VIP packages include line rental but if you want to have two lines you would need to take out another line with Virgin