pass on both, buy oem.
32bit is for 3gb of ram or less


http://www.newegg.com/Product/NewPro...-752-_-Product


64bit for more than 3gb ram

http://www.newegg.com/Product/NewPro...-754-_-Product

*Note u may have to buy a piece of hardware with it, go cheap like an sata cable, every vendor is different. These windows versions are for system builders and are FULL versions for the price of an upgrade disc.