Change Windows 7 in Windows XP

I had windows xp and 7 on my pc but I re-installed windows xp because of some problems so now it only boots to XP but i'm sure there's a way to add the windows 7 to the boot menu without having to re-install the Windows 7 again

I found solution:
1. Insert Windows 7 DVD and boot into it
2. Go to Repair computer > Highlight your W7 installation > Click Next > Get to the command prompt and type the following:
Bootrec.exe /REBUILDBCD

If the command is successful, close the Command Prompt window.
3. NOW Click “Startup Repair” to perform Windows Startup Repair. After doing these computer will reboot automatically.

If it works, and boots into W7 while seeing the XP dual boot option, then you're good to go.

If it works, and boots into W7 but has no option for XP, you'll have to run some commands in Command Prompt, in W7, which I have written below. Replace the driver letter in the third line with that of the XP partition.
a. Get to cmd in W7. Run as admin if you need to.
b. Type the following commands and press enter, one by one.

bcdedit /create {ntldr} /d “Windows XP Professional”

bcdedit /displayorder {ntldr} /addlast

bcdedit /set {ntldr} device partition=X:

bcdedit /set {ntldr} path \ntldr

When you've run all the commands, hit F8 at boot to see if it's all fixed.