Windows 8 can run Windows 7 programs and multitask. Essentially the biggest change is the start menu becoming the start screen, otherwise you can still use the OS like you would have.
Except as I understand it, that doesn't apply to the new metro apps and basically everything they're doing going forward. Everything new about win 8 seems useless at best and intrusive at worst to a traditional PC user. It's not like they're forking 8 off...this is their new vision for the laptop. It just seems insane to force this where it doesn't really work.