Hey guys,

well here's the scoop;
I created a partition a while back with vista 64bit and windows xp 32 bit. I installed xp first to create the partition, then installed vista on the other half of the hard drive. Everything worked fine. When I would start up my computer I was prompted for which OS I would like to boot from. However I had to reformat recently and decided to start new with Vista 64 bit and xp 64 bit. I started by reformatting my vista first, then went and reformat xp with my 64 bit version. Now when I start up it automatically boots into xp everytime. I tried editing the boot file in xp but i simply DONT know what line to add or what not to. i messed with it a bit and managed to give myself the option to boot from vista, but now when i try it says something along the lines of "ntoskrnl missing" and it cant start. I'm not sure if I even edited the boot file correctly. I'll post more details of what specifically I have in the boot file when I get home from WORK. I figured, i'll just boot from cd and rebuild the file, or wipe everything clean and start over, but now I dont even get prompted to boot from cd. it goes directly to my os select screen now. Can anyone assist? I would greatly appreciate it.

-PaulWhen you start the computer, do you see a message like "Press Delete to enter setup" (could also be F2 key instead of Del)?

As soon as u see that, press that. This will get you into the BIOS.
Here in the BIOS you can change your boot sequence.Yeah, I changed the boot priority to my cd rom first, but still, no option to boot from cd. It goes right to OS select.You said you messed with the boot.ini file.
Could you post that file here?certainly. when I get back from work i'll post it up here. thanks for your effort! ALTHOUGH the option to boot from cd stopped appearing right after xp6d bit was installed, before boot.ini was modified.XP here-----------------------Vista here
When you re-installed XP the boot sector is recreated,,,therefore all your boot files related to Vista are GONE as well.
You could try doing a repair install of Vista but i think for it to work properly you are looking at starting over again.

Please re-state how exactly you did this step by step as well as defining your drives/partitions layout...ok, I installed Windows XP 32 bit. Before I started installing it I partitioned the drive(C:) down the middle so it was now C: and E: at ~150G each. I Installed xp to drive C:. After Installation was done I restarted with vista ultimate 64 bit in the drive, boot from cd, and installed it to drive E:. Everything RAN fine, until recently I had to reformat my vista. I decided to reformat my xp as well so that I could run xp 64 bit. I reformat my vista with the same 64 bit version as before. When it was finished I restarted, put in xp professional 64 bit, boot from cd and reformat my xp to xp professional 64 bit. I started installing drivers for my motherboard, it restarted and booted immediately to xp. No prompt to boot from cd, no OS select, just directly to xp. I downloaded some boot managers because i didn't want to mess with the boot.ini as i had no previous experience with it. The boot managers were even more confusing, they didn't recognize my partition, and I had to work loops around it just to find my partition with vista on it. I uninstalled it and did a little research on boot.ini commands. So as of right now this is what I have in the boot editor on windows xp professional 64bit:

[boot loader]
timeout=60
default=multi(0)disk(0)rdisk(0)partition(0)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(0)\WINDOWS="Windows Vista Ultimate x64 Edition" /noexecute=optin /fastdetect
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows XP Professional x64 Edition" /noexecute=optin /fastdetect

Previous to how I have it set now, I had Vista set to partition(2). The computer would just restart when I would select it. I figured that was the wrong partition so I set it to partition(0) and when I select vista, it boots up and I get an error saying that ntoskrnl.exe is corrupt or missing and needs to be replaced or repaired. I checked the E: drive from XP and found that system 32 still has the file ntoskrnl.exe. So it must just be corrupt. However ever since xp professional 64 bit I am not prompted to boot from cd, regardless of the fact that my boot priority is set with cd-rom at the top of the list.

Hope that that's thorough enough! Any help would be so appreciated. Thanks!

-PaulOK.
First of all is the XP install having any hiccups at all ? ?
Problems booting, hanging or shutting down ? ?
If so i would run a Repair Install of XP

Then i would DLoad and install VistaBootPro....wipe the Vista partition and use it to do the Vista install.
Do you have a copy of the original bootini to revert to ? ?
If so do this before the Vista install. Vista handles the boot sector a bit differently than other flavors of Windows but if the XP install is intact there is no reason this shouldn't work...Untill recently I had a XP64/Vista Business dual boot.
I already had XP64 installed on my C drive, and installed Vista on a completely different drive.

Now in my boot.ini file on the C drive, it just had one line, only the XP line.
The real boot file came from Vista, who had created the dual boot file.

The standard OS to boot would be Vista (you know, the OS that starts after 30 secs).
But after downloading EasyBCD and installing it in Vista, I could easily change that.

So, my point:
CHANGING the boot.ini file (from your xp partition) wouldn't do you any good, since Vista creates the dualboot.

Well, thats how it was in my case.