Memory of 3 GB running full ?

My memory seems to be running full - this means in the Task Manager under "Free" often a 0 shows up. I added a Screenshot below which shows my normal situation.

I noticed that often for example Opera doesn't show pages correctly, even not at all. Opera eats plenty of memory as I see. But I also had problems with other programs hanging or not working smoothly ( e.g. IE8 ).
3GB are large enough or have I to add 1GB more ?

I also noticed that the memory is running out when my folder Sync program is working especially if the folder contains many files and dirs.

What does "Free", "Available", "In Cache" actually mean ?

I had the understanding that memory is somehow paged out to hard disk if necessary.

From the screen shot you are only using 72% of the total memory.

What processes are running? Sort by Working Set (memory) in the task manager.

pbcopter said:

What processes are running? Sort by Working Set (memory) in the task manager.

See Screenshot below.

I admit that I have many simultaneous processes running ( e.g. some servers ) and often I open about 10-20 notepad.exe files which start new processes. If I open several tabs in IE8 I have the impression that also each tab starts a process.

I am timid with removing processes I dont know.

Thats right. I regularly do that - perhaps a bad habit.

Do they interfere somehow with one another ?