Windows 7: Memory

If that is the green bar, that is a lot. It should be 1 to 1.5 GIGs. Do you have a lot of startup programs? If yes, disable them for a moment (not the AV program though) and see what happens.

If the startup folder I need is the "startup" in the "start" menu, it is empty!

I have a similar setup to you with 2x2GB and task manager shows with Firefox and system background stuff:
Total : 4095
Cached : 1974
Available : 3106
Free : 1245

What appears on the memory usage graph is Total - Available = approx 1GB
This is also what appears on the gadget gauge.

So it depends what you are reading. If my usage is 80%+ for extended periods then I think I have a problem.
I use memory intensive apps like photoshop and find 4GB is fine. I think it depends how many apps you want to run at the same time.

This kind of problem is new to me. Mine is as follows -
Available 652mb
Cached 634mb
Total 4095mb
Installed 4096
Free 12mb

I think that I must have a problem but I haven't a clue where to start.

Are these figures from Task Manager? Looks like a problem.
Try running Windows built in memory check first.

Press Start - Type "memory" no quotes
select "Windows Memory Diagnostic"
tell it to test now - your PC will restart & a memory test will happen.
It will take some time and a 2 pass progress bar will show.

First, can you post a snip of resource monitor on the memory tab?

Type msconfig into the start/search field and hit Enter. Then click on the startup tab. Then you see your startup programs and can disable them. Then reboot.

Let's ask someone else to confuse him further with another piece of advice to try first!!!
If he hasn't got a memory problem then the next logical step is to then find what's consuming the memory resources.

Let's start with the complicated things that take the most time then Your show, mate.

This isnt a problem at all. You are running 64 bit and minimum for that is 2 gigs. You have 652 avail, 634 cached. Thats basically 1.3 not used. the other 700 megs (4gigs- 2 for the system-1.3 basically free) is probably being used by the video card.

Is there another reason you think you have a problem?

Ken