Insufficient Memory Allocation

I am trying to install Windows Vista on my Parallels desktop for Mac. Unfortunately, when I try to begin this, it says "Insufficient memory allocated for Windows Vista (156 MB).The minimum amount of memory required to successfully run Windows Vista is 256 MB."

So I go to the preferences and try to change this, and the mamximum I can set it at is 244 MB.

Next, I go to the Configuration Panel, set the memory to what I need to run Vista, and I get this message.

"The memory size specified (268 MB) exceeds the recommended maximum of 192 MB. You must reduce the memory size otherwise you will not be able to start the virtual machine."

Has anybody else had this problem, or has any idea how to fix it?

Thanks.

 

Hi!
What is the total memory amount in your Mac? Remember that Vista requires at least 512 MB of RAM to run.

 

It's 512 MB 667 MHz RAM

At least that's what it says on the "About Mac"

 

drugsarebad: Well, that's simply not enough to run Vista. Parallels Desktop does not allow you to allocate more that 50% of your 512MB to a virtual machine, since this would cause OS X to freeze.