I bought a new computer with the Pentium E5400 processor, which is 64-bit. With it I got two Windows 7 Home Premium OEM disks, one for 32-bit, the other for 64-bit, and by mistake I installed the 32-bit version. How can I now change this to the 64-bit version?

You must do a full reinstall.

You cannot 'upgrade' x32 to x64 like you can Vista to Win7 or Win7 Home to Win7 Ultimate..

All processors are 64bit these days but are happy to run as 32bit too.

How much ram is in the computer, if it is less than 4gb you cannot install 64bit windows, infact you will get an error message telling you this.

Thank you, bkksw. The installation of the 64-bit version is running now. (I am posting this from another computer.

...How much ram is in the computer, if it is less than 4gb you cannot install 64bit windows, infact you will get an error message telling you this.

There are 2GB installed but I've got an additional 2GB on order.

So far, the installation of the 64-bit version has been running without an error message. It started with a message telling me that my computer was checked and then started expanding files.

I read somewhere yesterday that the 64-bit version of Windows is able to use 4GB memory more efficiently than the 32-bit version but did not say that 4GB is a prerequisite. I'll see how the installation goes. It may take several hours, I understand.

I have installed Win 7 64bit on machines with only 2GB and all okno errors, but agree 4Gb is preferred.

My bad, I gave some dodgy advice, I have just checked my install logs and I was trying to install 64bit office when I got the error (32 bit OS).

2gb ram is the minimum for 64bit, 32bit will also be fine on 2gb or 4gb, it wont see all of the 4gb though hence if you want 4gb or more install 64bit.

Installation of 64-bit version successfully completed. Now installing application programs.

Thank you all.

64bit version can be installed on a 2GB RAM system without a problem (I am using a virtual machine with this configuration every day).

Installing 32bit versions on systems with more than 3GB RAM is a waste of money, because the additional RAM can not be used.

This is the real driver behind the 64bit introduction.

Today you can easily buy 8GB systems. Only 64bit version can use that amount of RAM.

(good old XP was limited to 2GB of RAM, 3GB with some special kernel [hack]).

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You will probably experience minor compatibility issues with older applications.

Just post your experiences here.

Thank you, bkksw. The installation of the 64-bit version is running now. (I am posting this from another computer.

I'm glad it worked out for you. As you can see, the Windows 'upgrade' path is fraught with confusion. Microsoft needs to make it more simple.

You didn't say, but anyone running Win7 with 2g's would certainly appreciate the performance boost of going to 4-8gb (for a laptop) or 12-24gb (for a desktop) and at todays prices the upgrade would be very reasonable.