If you can successfully boot into XP, go to Start/Settings/Control Panel/System/Advanced/Startup and Recovery/Settings
There you will see a drop down for default operating system. Select the one you want to default to. You can also change the time-out value in the “Time to display” option. Deselect it if you don’t want to be prompted.
Edit your c:\boot.ini (assuming c: is your boot drive…change drive letter appropriately). You may have to “attrib -s -h -r c:\boot.ini” in order to do so (you should probably “attrib +s +h +r c:\boot.ini” afterwards to put it back to readonly, hidden, and system). You want to remove the extra lines you don’t want from the “[operating systems]” section, plus change the “timeout=30” line to whatever you want it to be.
In XP, you can edit the boot.ini file without all the usual mucking with attrib if you go to System -> Advanced -> Startup&Recover/Settings -> Edit. (Probably better directions here.)
save all essential files on cd or ghost them to a new hard drive, then erase the drive. reinstall windows xp with your password code. you will save many many many problems from happening in the future. use norton.