Both 32 and 64bit are available on the disk, I don't see a problem switching between the two if that's your thing

Because you don't remove one carabiner to hook onto the next rope without ensuring that your backup is secured.  Simple as that.

I'm running Windows 7 RTM already here's how it works.

Windows 7 will only allow you to install the version you bought - if you bought business 32bit you get the 32 bit version of  not the 64 bit version. so no you can't switch between them. In that sense it works just like Vista you enter your key and thats what you can install - if you choose not to enter your key and install the wrong verion it -wont- work.

Also the versions do not share the same disk the disk either has x86 softeware or x64 software - atleast this is how it works for the RTM version.

Same for the OEM version.

Hardware manufactures don't care they'll sell you what you want. What you need to worry about are softeware people - If you dont run ANY 16bit programs then you dont need the 32bit version bypass it completely. The 64bit version is fine now and the RTM doesnt even go public until the 22nd of October - drivers are there, it feels like a MS OS that has already seen SP1 - so unless you've got really really old software on your computer that you cant run in a VM just buy the 64 bit edition you wont need the 32 bit version.

You would have to create 2 partitions on your harddrive, install 32 bit on one and 64 bit on the other.. But since you used the product key (lets say) for the 32 bit edition activation, you would need another key to activate the 64 bit version.. When you boot up your computer a boot manager will display asking which version (partition) to load.. The biggest problem with 64bit is you are limited to newer software..

Although there is software that will allow Windows 7 to run a virtual XP enviroment.. So you could run XP software

Thank you Rob.  That's about what I needed to know.

Any idea if you can upgrade vista 32bit to windows 7 64bit? Because the morons at HP put a 32 bit os on my laptop with 4gb. I've been running the windows 7 beta (64bit) since i bought it.