Agree with that, a lot of machines that are that sort of spec do seem to fly well with 1 or 2GB Ram.
Memory always makes a massive difference. I have a PC at home just for the internet, it's a Duron 1100 and had 256Mb RAM I was about to get rid of it as it was really slow but I came accross 1Gb of RAM I had spare it has a new lease of life now.
On my home network; slowest server is a windows 2000 DC with 300MHz PIII with 256MB RAM, slowest workstations ia a 900MHz PIII with 1024MB RAM i think.
At work slowest server is 2.8GHz dual Xeon with 2024MB RAM. Fastest is 2*4 core Xeon @ 3GHzish with 4GB i think.
Our email server must be based on one of the earliest Celeron chips (1998/1999?) running Windows NT and mail server software nobody seems to have heard of. Good job we only have a handful of users on it. I'm actually scared to reboot in case it doesn't come back on! I can't wait to retire it.
To be fair though, out of all the servers it probably gives me the least amount of trouble!