Installing 7 on Acer Aspire 5315

A friend has asked me to install Windows 7 on an Acer Aspire 5315 laptop.
No problem I said
I set the boot order to boot from disk and put the disk in.
Instead of the expected "press any key to continue" I get a black screen with "select CDROM boot type:_" with a flashing cursor.
I'd never seen this before but I attempted to type in "normal"- a guess- and it seems I have no keyboard input at all. I tried all the letters and numbers plus Fkeys and nothing.
I cannot type anything in.
I than tried ctrl/alt/del and this ended the process but that seems to be the only key combination working.
I'm wondering if it's because I'm trying to put x64 W7 on a Vista x86 laptop and some kind of EFI protection is kicking in.

Any ideas would be most welcome

You cannot put a 64-bit OS on a 32-bit PC.

Well it would no longer be a 32 bit pc if I installed a 64 bit Os on it.
I'm not trying to do a dual boot but a clean install. The hardware would run it. Don't see the problem.

Ahh... if you have 64-bit architecture, then you are correct you cannot upgrade from a 32-bit Vista to a 64-bit Windows 7. It would have to be a new installation.

Thanks for your input Lemur:)
Yeah. That is what I am trying to do. Lose Vista x86, reformat the disk and clean install W7x64.
There is a form of data protection called EFI which I'm not familiar with. I believe it's designed to prevent someone stealing/finding your laptop, installing another OS and accessing your data and I have the feeling it may be something to do with that.
Not sure at all though.
I've mailed Acer about it so I'll see what they say.

Just more info. This is straight off Microsoft's site:

Can I upgrade from a 32-bit version of Windows to a 64-bit version of Windows?

No. If you are currently running a 32-bit version of Windows, you can only perform an upgrade to another 32-bit version of Windows. Similarly, if you are running a 64-bit version of Windows, you can only perform an upgrade to another 64-bit version of Windows.

I'm not upgrading. I'm trying to do a clean install. I did the same thing last night on another pc running 32 bit XP. No problem.

Thanks Greg and Lemur.

Seems it was the EFI protection kicking in, responding to a x64 install.
This is primarily aimed at Linux installations to access the Windows install but responds to any x64 software.
I found some things I could have tried to bypass it but that would have encrypted the Vista install.
As I was setting it up for someone else I contacted them and they had only wanted a x64 install because they had read x64 was better.
Consequently I installed x86 W7 without any problems:)

Thanks for your input, John