Options 
1. Download Windows 7 - format your book - install 7 
2. buy windows 7 - format your book - install 7 
3. dual boot windows - check link below
http://www.pcworld.com/article/2012070/how-to-dual-boot-windows-8-and-windows-7.html

btw you can do your hdd partition without formating your pc by using third party softwares like partition magic, there are lots of free partition tools 
like this http://www.ilovefreesoftware.com/18/featured/5-best-free-partition-software.html

well i have dual boot 8 and 7 - i lop win 8 :) , just get used to with it you will lop it :) 

let me knw if you need more info 

thnx

good luck