It depends which day I answer the question.
As I have mentioned on other posts, I have used free computers which other people discard for Tiny Core and the internet. Thousands are being discarded every year. I also swap parts. For example, I take the one with the fastest cpu, put in the largest ram and hard drive.
A few years ago I obtained a 667 mhz computer, which had 512 mb of ram. I used that for a few years.
Recently I have tried others. I used an 800 mhz computer for awhile, then a 1.5 ghz computer with 256 mb of ram.
Since then I have obtained a 1.6 ghz computer. When I first used it I had 1 gb of ram (2x256 and 512). Since then I obtained a 1 gb ram sim. I took out a 256 mb sim and put in the 1 gb, giving me 1.75 gb. However, with that combination the computer would malfunction on rare occasions. This is the only time I have experienced this. Normally ram works or doesn't work. As a result I removed the other 256 mb sim. I am now running 1.5 gb (512 and 1 gb).
I voted as 1.5 gb. That is what I am using now.
You can never be sure what will happen tomorrow, but it is not very likely I will come across a higher performance computer which someone is discarding for some time. But you never know.
Edit: Since posting this, I have picked up a 2.4 ghz computer. It is amazing what people throw away. I am now running this 2.4 ghz computer with 1.5 gb of ram.