FREE Express Upgrade to Windows Vista Business Edition Note! This product must be purchased in conjunction with a hardware item. Full Version OEM Differences between the OEM and retail version of Windows XP are the following: Retail version comes in a fancy box. OEM does not. Retail version contains a printed manual. OEM comes with an instruction booklet. Customers who purchase the retail version are eligible for tech support from Microsoft. Retail version offers the option to do a "Quick Install" or a "Clean Install." OEM version offers the "Clean Install" option only. However, performing a "Clean Install" is HIGHLY recommended. The OEM version costs approximately $100-$150 less than the retail version.