64 Bit Installer says it's made for 32 bit and tells me to install 64 bit

Have you tried first completely removing the iTunes application? (Your media and library are contained in /Music/iTunes and will not be affected by removing iTunes)
See this -> Removing and reinstalling iTunes, QuickTime, and other software components for Windows Vista or Windows 7

I have had the same problem. Did you ever get yours to install or upgrade?

I had the same problem. I used PC mover to move files and etc to my new PC. Old pc was Windows Vista and the new PC is runing WIndows 7 64bit. I have talked to tech support and still no luck. I am waiting for a call back. Where ytou able to find a solution to RJ error as well. Ihave tried to removal. Itunes will not move and another file will not remove. Still are unable to upgrade to Itunes 10. REcieved another phone and was trying to complete restore it told me that I needed Itunes 10 but unable to upgrade. ANd I get the same message as RJ. about the 32-bit and 64-bit.

I download the new 10.1 for 64 bit operating systems and during install it tells me that this installer is for 32 bit systems and I need to install the 64 bit installer!!!

Yeah, it's actually the 32-bit version that PC Mover has wedged into the new 64-bit PC that is returning that 32-bit message. (When you try to install the later version, the installer tries to remove the previous version which suddenly realises it is on a 64-bit system, and everything turns to custard.)

In the best of all possible worlds, I'd prefer to remove the 32-bit iTunes by undoing the migrstion (using the PC Mover undo function). Unfortunately, my understanding is that you can only completely undo the entire migration.

If you aren't keen on that, there's an alternate strategy described in the following post:

http://discussions.apple.com/thread.jspa?messageID=12712585&#12712585

You may not need to search for a copy of Windows Installer CleanUp. In his/her reply to that post cmcmd reports:

Fantastic! I contacted PC Mover and they sent me a link to the Microsoft Clean Up utility. I deleted all of the Apple files, installed teh 64 bit iTunes and all appears to be working.

So you could perhaps try your luck with PC Mover too. Fingers crossed the support person you get through to will also have the link to the CleanUp download.