bootmgr and bootmenu is on winxp partition! If you format it... it's gone.
Simply reinstall winxp
Then perform a startup repair from Windows 7 installation CD or Windows 7 rescue CD.
Then add winxp to the Windows 7 bootmenu using easybcd
source Dual Boot Installation with Windows 7 and XP
On the left side of EasyBCD, click on the Add New Entry
button. (See screenshot below)
A) In the top section under Operating Systems, click on the Windows tab. (See screenshot below)
B) To the right of Type, select Windows NT/2k/XP/2k3 from the drop down menu. (See screenshot below)
WARNING: Be sure to leave the Automatically detect correct drive box checked.
C) To the right of Name, you can leave the default Microsoft Windows XP as the name to be displayed in the Windows Boot Manager, or you can type whatever name you would like to have instead. (See screenshot below)
D) Click on the Add Entry button. (See screenshot below)