Windows 7: after xp installation i lost windows 7!!

Hi all ,,,
I'm new to windows 7 forums , I hope I can help and you can help me also.

I installed windows XP professional on my Toshiba laptop which contains windows 7 Home Prem.
when I finished installation the Default OS changed to XP and I tried to boot to windows 7 but I can't.

now I have format the partition (by using linux live CD) which contains "windows xp" but the boot failed to load windows 7!!!

it gives me a message system32\hal.dll is missing !!
so is this for windows 7 or windows xp??

I didn't touch windows 7 and the files still there with no change!!

any one can help me in this ,,,
I need my machine to load windows 7 again but I cant


any help is appretiated
Thanks

There's about a dozen ways to go about this, the least intrusive one (though granted not very likely to solve this) would be to start with a simple startup repair, you'll need your windows disk for this.

I am hoping you didn't install linux's grub during any of this, I'm also hoping you were careful enough not to actually overwrite win 7 when installing xp.

Startup Repair

now if that fails, and it very well might.
This is probably the most hassle free fix for you.
Repair Install
It will reset windows itself to default settings but your programs and files will remain as they were.

There are some other less drastic methods but I don't have a whole lot to go on here and a repair install will fix anything you've managed to mess up with the xp boot data.

I'm sure i didn't overwrite windows 7 , because i have made a new partion for windows xp and i installed on it.
I don't know if it's automatically overwritten!!

and about linux also i didn't install linux's grub

about startup
the problem is that the choice of (repair computer) does not appear right now!!
before installation it was there but now when i press F8 the first option is safe mode and the others after but computer repair is not there!!


about repair install
I can not enter the windows 7 itself, the machine can not load the windows and it gave me the system32\hal.dll is missing!!

thanks Maguscreed

startup repair is not working either?

hal.dll is because it's still trying to use the xp boot data. You need to restore the windows 7 bootmgr, startup repair should be able to do that.
Startup Repair

it's working using windows 7 installation, I have using startup repair now and it restarted.
another problem comes againg
system32\ntoskrnl.exe >>> it says it's missing or corrupt!!

but my windows 7 can't be loaded till now!!


any help in this
thanks

hmmm well if you can get to Safe Mode with a command prompt that's all we need to run this.
SFC /SCANNOW Command - System File Checker

Please pass along the results of that scan.

when safe mode tries to start this message is displayed

multi(0)disk(0)rdisk(0)partition(2)\WINDOWS\system32\ntoskrnl.exe
windows could not start because the following file is missing or corrupt:
<Windows root>\system32\ntoskrnl.exe
please re-install a copy of the above file.


thanks