Sounds like you reinstalled W7 without wiping out the partition table (thus the remaining XP boot option in the BCD menu). Reinstallation of W7 or any Windows OS is best done if the ENTIRE hard drive is formatted using the W7 install program or other utility such as DBAN. The issue here is that W7 on most OEM computers contains a utility such as ACER e-Recovery that allows you to make a set of factory DVD Recovery Discs containing your original OS (XP or W7) or a factory USB Recovery stick. Also, most OEM PC makers also install a hidden factory Recovery Partition on their C: drive which also contains this same image which contains your original Windows OS that came with the computer from the factory and contains Windows and all the utilities and other apps programs such as MS Office, AV, freeware, trialware, etc. that was on your PC when it came from the factory and can return it to OOB (Out-Of-Box) condition.
This means that hopefully, you have created those DVD/CD discs or USB stick prior to wiping out your Data Partition (XP) and replacing it with W7. If you failed to do either of those things, you can't go back to your original Windows (XP) easily. Your PC can be rebuilt manually by a professional Computer Tech for $$, or you can call up the PC maker on their support line and attempt to purchase the factory Recovery Media. This will typically cost $29-$99 US; but if your computer originally had XP on it, it can be from 9-15 years old now as of course you know XP has been obsolete for over 2 years now (April 14 2014), and most PC makers no longer keep or will sell you Recovery Media for computers that old. Sometimes you can find them on aftermarket sites such as ebay; but that's still a crapshoot to get something that works.
Be aware that if you follow OJ's recommendation, you may be destroying that built-in factory Recovery Partition that came on your hard drive. This can cause you great problems with windows licensing and activation if you don't have an actual key for your W7 (non-legit upgrade).
Check if you have Recovery Media first. If you have gone past that step already and completely formatted the C: drive at some point in this upgrade or repair process; you'll have limited options to fix it. Also, if this computer was self-built by you or a local custom-PC shop, and they or you installed XP onto this machine, and there were never Recovery Discs made or available, it's going to be quite difficult to resuscitate this computer.
Hope that neem's BCD fix works.
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