Well, HSDPA is just another way of connecting to the internet. As long as you can open Google on your computer, your XBOX will be able to connect to live.
Some updates: I am thoroughly enjoying the "New XBOX Experience". It's much prettier than the previous dashboard and the avatars are pretty cool - you can take a picture of your avatar and use it as your gamer picture! Try waiting for your avatar to do something cool and take the photo...
The HDD install feature is a blessing - no more whirring from the box constantly reading the disc, Unreal Engine 3 games have less texture pop-in and (some) games load a bit faster!

The XBOX Guide has also been improved a lot and it's easy to access your system settings, achievements, media, etc. while still in a game... Very cool indeed.
Hope you all enjoy the download tonight! It took about 25 mins on my HSDPA 1.8MB.