Assistance needed, cannot access desktop

Okay, i just recently ran into this problem. But first a little background is in order.

I am running a custom built desktop with a 640GB hard drive. on this hard drive i have windows xp pro 32-bit installed
and the 64-bit version installed. (For those of you who are wondering why i have both, the reason is because i needed the
32-bit version to get drivers for the 64-bit version) They are on separate partitions and the active partition with the boot files are on the 32-bit partition. all my important files, including many programs that i had to modify to work for 64-bit, are
on the 64-bit installation. i barley use my 32-bit edition unless, like now, i am unable to work with the 64-bit.

earlier today i was messing around in my partition manager, I use Acronis Disk Director Suite as the moment, and decided that i wanted to change the active partition to the 64-bit version. well at the time i didnt realize that there were no boot files on that partition since i installed the 32-bit version first. the change required a reboot so i did and after bios loaded i got the annoying error, "Missing NTLDR Reboot etc..etc." At this time i have absolutely no way of booting my desktop computer. so i get on my laptop and start troubleshooting. since i have encountered this error before i knew how to solve it. at first i though i had to use FIXMBR AND FIXBOOT, like in the past, to solve the problem. also for some reason i am always denied access when trying to copy NTLDR and NTDirect fiels to my hard drivie. but eventually i found out i had to switch back the active partition to the one with the boot files. after downloading and burning a recovery
disk that contained FDISK i was able to switch that and boot my computer.

i am able to boot both operation systems, but only one gets past the login splash screen. on the 32-bit OS i checked the 64-bit partition for any errors and nothing came up. I use NOD32 antivirus and so far have had no problems, so i dont believe the issue is with a virus. when i select the 64-bit OS the windows loading screen shows up(the one with the moving bar) and then it changes to the blue login screen. except it never gets past the tiny windows logo and i never see the welcome message. it just hangs there not doing anything. i have only one user, the admin, so if it were to boot correctly it should go right to the desktop.

i really dont want to have to reinstall the OS. i dont have any crucial files, but i have put a lot of work into modifing A LOT of things. any thing i do need, though, i can access from the 32-bit version. the drive is still working and i can see all the files. i just cant get to the desktop.

any help would be greatly appreciated.