Hi, The Vostro 420 has not been tested by Dell with Windows 8. However if you are using Windows 7 on your system there should not be any compatibilty issues.You can also check whether the hardware DEP is available on your system by doing the following steps. How to confirm that hardware DEP is working in Windows: After the official launch of Windows 8, the drivers may not be available on the Dell support site. However, you can always check the manufacturer's website for suitable drivers.You can also check the following link for any further information on Windows 8 upgrade.[URL]  
Vostro 420Windows 7 64-BiBios 1.3.0 (latest update, released 2010)Hi:Can the Vostro 420 run Windows 8 when it is released next month?  And, does the Vostro 420 bios have DEP support? (I read Windows 8 needs a bios with DEP support) Thanks
Windows 8 Compatibility with Vostro 420 BIOS v1.3.0