Windows 7 >>> windows xp switch problem :|

ok look people i have a problem here...and Im in a hurry
so i'll just decribe what happened and some important info
so i have friend who had a fine pc
it had windows 7 installed in it...
he wanted me to install xp in it as he felt it was operating too slowly
so what i did was took a windows xp sp2 disc and inserted into his dvd rom
restarted his pc....the 'press any key to boot from cd' screen came up....and i pressed a key
after that the partition screen came up where you have to choose the drive where you install xp
so there was a wierd thing here
the C: partition was of 100mb
whereas in the OS it showed 74gb
so we figured out that the 'C drive' referred to 'D partition' in the 'partition screen' i.e the C drive in the OS was 74 gb and the D partition was 74gb too
in short they were the same
and one more point about the C: partition....it couldn't be deleted or formatted or whatever
so i was like okay i'll just format D partition and install xp in it
so i did it....i formatted it with 'ntfs normal' no the quick one
after that the setup started installing the basic files like those bus drivers etc......after it was 100%......the pc rebooted then the 'press any key to boot from cd' screen came up
i knew that any keys arent supposed to be pressed here
so after a few secs...there was a message like this:
'press any key to boot from cd....error loading operating system'
i was confused....so i just got another xp cd which was sp3 pro
i installed it the same way.....and this time the error didnt come up
but instead the screen stuck at ''press any key to boot from cd''
i was so damn confused again....
so here i am...i have wrecked my friend's pc....he's angry at me....and im asking for help here....you guyz have helped before so im counting on you'll i have faith...
awaiting a quick reply
cheers n peace

EDIT: reply.! anyone! please....

EDIT:can spotmau powersuite 2010 cure this problem?

EDIT:c'mon ppl! :(