Hi Surryguy
Basically skyHD is going to cost you extra (�10 per month) as well as upgrading your tv and box. Will this provide you with a better viewing experience? honestly it is doubtful at the moment. HD tv's are not upto scratch yet, they are capable of receiving HD pictures but they don't show them in the best light ( few exceptions but very expensive) also the content from sky may not be in the best just yet. Personally I'd hang on for a bit, prices will start to tumble soon as well.
The other thing to consider is program choice.