2 GB Memory Limitation

Hi. I have used Parallels 6 for a year or so now, and very pleased with it. I have run it with Boot Camp, but now want to run virtual without Boot Camp. I am doing a new VM installation and I have a 2 GB limitation from parallels. I have 8 GB of RAM and I'm installing Win 7 Ultimate (64-bit) over Snow Leopard 10.6.8.

It will allow me to choose 4 GB of RAM but tells me it will cause problems. When I ran Parallels with Boot Camp, I allocated 4 GB and 2 cores to Windows, 4 GB and 2 cores to OS X and it flew.

While I can just go ahead and make the change, I'd appreciate any insight into this and whether or not I should do it.

Jonathan