| I've checked that link and the %age idle time is running very close to the top of the scale and the %age processor very low, is this normal? |
If you click the "View Report" button after adding the percentage processor and percentage idle options for display, you will see a numerical percentage of both, which should add up to %100 total for both.
The percentage idle nemerical value is telling you the percentage of the processor that is "idle" or not in use.
The percentage processor numerical value is telling you the percentage of the processor being that is "active" or in use.
You want the idle number to be a higher numerical value, and the processor number to be a lower number.
Note - this test only reflects the processor active and idle percentages, and does not indicate amount of RAM being used up.
For an easy overall RAM check, you can perform a boot into the default "Luna" theme with no other customizations loaded, and then look in "System Information" (Start > All Programs > Accessories > System Tools > System Information).
The System Summary page will give a value of "Total Physical Memory" and "Available Physical Memory". If you subtract the Available from the Total, you will have the current memory used by the default theme.
You can then load programs and use the changed values to deduce the amount of RAM being used by the loaded programs. This should give you an idea of whether the additions of specific programs are grabbing a lot of memory, or if it simply adds to an already limited amount.
Task Manager just shows the individual values, but System Information is sometimes a better way to see the overall picture on memory use during normal operation. Task Manager is great for tracking a process that is hogging memory.
Sorry if this is just too basic, but I find the combination of System Information and Task Manager a good way to grasp the memory issue. 
