Anything lower than 512 megabytes won't do it justice. I personally have two gigabytes of memory on my system and I allot one gigabyte to each OS when, and if, I boot Vista using Parallels. But I used to do that when Vista RC1 was released to check it out. Don't do it any longer now... for obvious reasons!
Tiger has really got a huge jungle to play in, and boy, it is fast! I selected thirty images, right-clicked and selected 'Open with Photoshop CS2'. The program was already running and the images opened in cascaded windows in two seconds flat. And this when Mail, Safari, iChat, iTunes, iPhoto, QuickTime, System Preferences, Adium, Microsoft Messenger, Opera and Yahoo! Messenger were already running.
I then booted into Windows XPee (using Boot Camp) and launched Adobe Photoshop CS2. Then I selected the same thirty images and hit return. It took
twenty two seconds even with no other program running. Let's hope Windows Vista is not blown away so easily by Leopard... or even Tiger!