With SQL Server 2005 Standard Edition the memory it can use is the maximum memory of the server. So in your case the 4GB of RAM (which is actually around 3.2GBs) Express is limited to 1GB of RAM
There are pros and cons to each as SQL will continue to use more and more memory for pages and procedures. Fortunately, you can set a maximum of say, 2GB.
I had no issues with Amazing Charts creating an instance with SQL Server 2005 and not Express. I just removed the SQL Server 2005 instance components and then removed the AmazingCharts: Database engine. Of course, everything was backed up for reinstalation.
I am a little confused about what you mean when you say you are only using 1% of the bandwidth available.
Of course, the other solution would be to install a 64-bit OS and add RAM, but then Express can still only utilize 1GB of RAM.
In your situation, my sense is that SQL Express would grab its 1GB almost immediately, leaving you with about 2.2GB of RAM, which should be plenty to run your other programs including SQL and AC.
If you go to Task Manager | Performance (tab) |Physical memory, what is the breakdown of memory there, especially the free memory.
And, when you go to Task Manager |Processes (tab | then click on the memory section of the row above the processes until you get the processes with the highest amount of memory, is SQL at the top; and how much memory is it using?
