I work for SKY so it may sound I am a little biased but before working for sky I was with Virgin Media, they always charge quite alot weren't with them when they had HD, but the HD box with SKY is fab

, if you didn't want to pay for HD (£10.25 per month, for 12 months) get a MR (multi room subscription and it will be free

)
SKY Always add more HD Channels too, dependent on contracts with company's but they got more choice than VM!... your choice
*this is from a personal view not a company's lol!