I currently have Sky HD with the full sports, movies etc bit had been reading about how you can get a jailbroken Apple TV and view lots of content on that.

How would it compare to Sky HD & is it a worthy replacement or would it be more of an accompaniment?

What you are talking about is quite a leap from a Sky HD subscription to a jailbroken ATV2 probably with XBMC or Plex running.

Although the ATV2 and XBMC/Plex is nice and can offer a reasonable amount, it is possibly quite a steep drop from what you already have.

The next logical step down would be FreeSat and if possible FreeTime (which is FreeSat with the catch-up services) or indeed FreeView which is terrestrial services + catch-up.

Sky HD is a great subscription service for live TV, which also offers other features, and the ATV2, jailbroken is less of a live TV service, but more for internet streaming. They are quite different.

If internet streaming is your planned route, keep an eye out at this website: www.eyeondemand.com
It's new, but it's goal is to explain what is available out there regarding on-demand and catch-up services, and basically internet television in general. It has a global viewpoint, but will be very strong on the UK angle as well.

I personally started with a Sky subscription and downgraded that to FreeSat which I was really happy with. In my new apartment, I can't have a satellite dish, so I have since switched entirely to Internet television.

There are an enormous amount of services out there, ranging from free to PAYG and subscription, as well as an endless amount of devices. Making the right choice is not as easy as it may sound, especially if you want everything on your television and as sofa friendly as your Sky HD package is.

But, it may very well be possible. The hardest part really is affordable sport. How important is this, and how often do you watch it?

Movies are easy though, as with television. I love Netflix, and what I can't find on there, I can get from a Pay-As-You-Go download from iTunes or elsewhere. All up, it's probably a lot cheaper than a Sky subscription.

If you think a jailbroken Apple tv is gonna compare with Sky HD you better think again,I have both with XBMC on my pc and ATV and Tab 2 and iPad 2 and there is no comparison wotsoever.To get any reasonable streaming you need a fast broadband connection and when and if you find the match etc the streaming is by and large hit and miss with buffering etc.Nope you cannot compare the two.I only wish you could..

^^ I agree with that. XBMC and Plex are magnificent programs, but they do often have issues with their 3rd party plugins.

There are some things on the Apple TV (and I presume Jailbroken as well) which can compete with normal services.
Netflix for instance is great. There is no question of course that Sky HD will have a lot more recent movies than Netflix. But if you add iTunes rentals for new releases, and Netflix for the catalogue, it makes a fine combination that covers most films for less money. Add FreeSat (FreeTime) or FreeView into the picture and you may have something that is pretty good...

But you still lack all those broadcast channels that Sky HD has, and that won't be easily replaced with anything, let alone only a jailbroken ATV2.

Experiment with XBMC, download on your computer and see how it fits you with all of the plugins that way.