SimonXuan,
No, MCE PKs are not interchangeable with Home Edition.
If you received no MCE CD, that means you have Dell PC Restore by Symantec installed. Search the Dell support pages for detailed instructions on how to use it to reformat and reinstall. Dell will sell you a reinstallation CD, contact their tech support.
To access Dell PC Restore, restart the computer and at the Dell startup logo, press and hold CTRL, press F11 then immediately release both at the same time.