The release date over here in the UK I believe is 22 October 2009, with pre orders available now in most places (while stocks last).

Prices are as follows: GBP(£) prices with USD($) in brackets

Retail Prices (UK) - Home Premium £149.99 ($251.36), Professional £219.99 ($368.68), Ultimate £229.99 ($385.44)
Amazon.co.uk - Home Premium £69.93 ($117.19), Professional £159.99 ($268.12), Ultimate £189.97 ($318.37)
PC World (UK) - Home Premium £69.93 ($117.19), Professional £99.97 ($167.53), Ultimate £189.92 ($318.28)

I am not certain how well PC World are known in the US or other areas of the world, I have soley mentioned them as they are one of the largest stores in the UK for computers and accessories and they seem to be offering one of the most competetive deals on Windows 7. They do state however that these prices only remain whilst stoks last and they are limiting pre-orders to 3 per customer.

I have heard rumours that certain outlets are offering a free upgrade to Windows 7 on Laptops and PC's purchased with Vista installed before the Windows 7 launch, I am not entirely sure how true this is or what package the upgrade will be to (Home, Pro, or Ultimate).

That doesn't sound like the half-price sale. It actually sounds like a full license. Over here the half-price sale was for the upgrade but not for the full license. The upgrade is cheaper anyway. Home premium was 49.99 USD and pro was 99.99 USD. The Ultimate version was not included in the sale. That price was set by Microsoft so all of the companies followed it.

They are also offering a free upgrade on certain models as well as a retail purchase of Vista and the version should follow along with the version that you bought. Vista home premium = 7 home premium; Vista business = 7 pro; vista ultimate = 7 ultimate. They aren't going to offer a free upgrade to a more expensive version than what you got. I guess if you get a computer with home basic you are out of luck (but I don't know that for sure) because there is no 7 home basic.

To run 7 well you just need to get a computer that will run Vista well. What applies to everyone is a minimum of 1 gb of ram & 2 gb recommended; Anything less than a gb will result in poor performance. If you have a computer for special needs (games, video editing, OS emulation) you will need more resources than someone who just uses there computer for what I call "light computing" (ie internet, light games, office, etc). The ram is important; everyone that I've known that doesn't have enough complains that their computer is slow.