With 1gb of RAM, you should not use memory benchmarks to choose a distro, in my opinion. If Distro A uses 100mb of RAM and Distro B uses 150mb (for the sake of argument) that tells you nothing about which distro will be faster on your hardware, more stable on your hardware, more user-friendly, best support over time, have a better community, etc.
If you only had, say, 128mb of RAM, then you would see a big difference between 100mb and 150mb. But you don't--you have 1gb--so none of the distros tested will use over 20% of your RAM.
ps Debian 5 is coming up on its "end of life"--not recommended!
Last edited by snowpine; 12-20-2011 at 11:05 AM.