I am running Windows Vista Service Pack 1 64-Bit. I need to install SQL 2005 32-Bit but I am not sure about the minimum system requirements for the installation. Can I install it in my 64-bit PC? Will it cause any issues? Please send me some guidelines on how to do it correctly. Thanks.
You can install either the 32-bit or 64-bit of the developers edition.
If you are just installing the client tools don't bother to install the 64-bit edition as the client tools are only 32-bit.
You can install any software of 32-bit on 64-bit but you cannot install any software which is 64-bit on 32-bit
This is how every upgraded system can run its previous versions
 but previous version cannot run upgraded system
Yes you can install sql server 2005 32-bit on 64bit vista easily.
Actually all the upgraded architecture of operating system are supposed to be backward compatible with their older versions. lt is exactly like if you ask to a graduate level student to elaborate primary education course book. This will not be a big deal for a him. but vice versa is really not possible. you cannot ask a primary level student to elaborate graduate level things.
Likewise those programs/softwares which are successfully compiled to the 32bit(x86) standards, can easily handled  by 64bit(x64). Although the 32bit(x86) instruction set is different/ degrade from 64bit( x64) but understand that the x64 first includes everything of x86 then the newer approach and modifications.
