Microsoft’s on-the-box minimum RAM requirement “really isn’t realistic,” according to David Short, an IBM consultant who works in its company’s Global Services Divison. He says users should consider 4GB of RAM if they really want optimum Vista performance. With 512MB of RAM, Vista will deliver performance that’s “sub-XP,” he warned.
As if Vista wasn’t expensive enough, you should now add 4GB of ram to your shopping list. I have used Vista quite extensively and never had a problem with only 2GB, but I could see 4GB being far preferred if you are doing a lot of multitasking.
Source: Computer World