I honestly have forgotten ..... i think there shall be a folder called windows.old or something like that; same goes for program files.
I am guessing here because I have not seen this situation in so long now. You can manually erase those folders (only these folders that is).
However, to remove xp entry from win7's boot loader you have to follow these steps:
1. Click on Start,
2. Go All Programs, then Accessories
3. Right click on Command Prompt and select "Run As Administrator"
4. type bcdedit it will give you boot loader's existing data/settings
5. type bcdedit /delete {identifier}
where identifier should look like this:
Heading:
Windows Legacy OS Loader
identifier <ntldr>
Before pressing enter carefully examine what you have typed to ensure accuracy, once you press enter the Boot Configuration Data Editor (BCDEdit) will remove the entry for the ID you specified and display a message when finished. When Windows starts, the only choice available in the boot menu should be the current Windows installation.