When ever I try to start up my May 2009 MacBook I have to hold down the "option" key and the select the "Macintosh HD". I tried to install Windows XP on it one time but I canceled during installation does any body know how to fix this or somethhing
You should be able to run Boot Camp Assistant and remove the boot camp partition...restoring your drive to its former single partition state, assuming it made that partition already.
To remove Windows from your computer:
Step 1
In Mac OS X, quit all open applications and log out any other users on your computer.
Step 2
Open Boot Camp Assistant, in the Utilities folder in the Applications folder.
Step 3
Select “Restore the startup disk to a single volume,” and then click Continue.