How to delete a primary partition?

I have windows 7 ultimate and i also created an empty primary partition separately. Now my problem is- i want to delete the primary partition but how? I read somewhere that using xp disc by booting and deleting the partition my problem will be solved. But when i use xp disc and delete the partition during setup, windows 7 won't boot next time. I used recovery disc of 7 but no use. The only way is to install xp in a partition and then use the system recovery disc to get windows 7. Even then the primary partition won't get deleted because it is as xp drive. But i don't want two os. I just want to use windows 7. For your information, i have the 7 partition, a logical ntfs partition and that unnecessary primary partition. I want delete that last one. Help me, plz.