ok, small exageration.
i'm on P4 1600 mhz
384 something ram
sapphire radeon 9600 pro
i bought rollercoaster tycoon 3 last week and i was getting a steady frame rate of 10-15 fps on low settings but when i got 300+ visitors it was just intolerable. my brother said try on 'ME' you might get a slight improvement. so i put a fat32 partition on my second hard drive. now i can run it smooth on medium to high settings (with full reflections) depending on park size at a good frame rate (couldnt be bothered to check framerates with fraps but there isnt really any slowdown till 500 and it isnt bad until about 800 guests.)
so the secret is use windows ME for your games. BF vietnam can handle twice as many bots now but CoD wont play.