Windows 7: How much RAM

On my desk top computer I have WINDOWS 7 with 4 GIG if RAM. I installed VMware and will install XP as the guest. Since I have 4 GIG of RAM on the host machine, wouldn't it be a good idea to assign at least 1 GIG to the guest machine since it will release it back when I'm on the host machine? I think I read somewhere that you should not put more than 512MB. Is that correct about the 512 MB?

You have enough ram memory... So gave the XP 1GB of ram. Will be good.

First of all it matters on what you are going to use it for, but for anything i recommend using about 1 GB of RAM.
It don't matter how much RAM you use on a virtual machine, because a OS would work better if you had atleast 1GB. Expecially 1GB

Thanks for your quick response!

VM's will not be using the RAM if they are shut off. Give your VM as much RAM as it needs. I frequently test machines and dedicated 2GB and sometimes 4GB of RAM to them.....you certainly "CAN" allocate more than 512MB if you need to.