Now i am assuming that the difference between 768MB and 558MB (210MB) is used for the operating system, which i guess can be expected
The problem i have is that even with 558MB available and when i have killed every Application/Task that i can i only ever really have around 200MB available!
What is using this RAM is it Sense and/or other automated Tasks running in the background that you cannot kill?
I have noticed that some tasks that you kill (like the ridiculously annoying Vodafone 360) keep re-launching themselves. Is there anyway to permenantly disable these to free up more memory?