I have been using the components from the following site:
http://www.wilsonc.demon.co.uk/delphi.htm
You need to download and install the following:
1. lanmanutils;
2. miscunits;
3. miscutils;
4. ntcomp; and
5. ntutils.
There is a demo project included.
The other thing to consider is what you are doing with the value that you are receiving from getcpuusage.
I apologise in advance if you already know this but the figure that you are getting is a string (originally a double) which needs to be converted to an integer because this is what the gauge requires (assumes you are using tgauge but progressbar and trackbar also require an integer). This is the routine I use to convert (there is probably a better one!):
function floatToInt(dblFigure: double): integer;
var
intRoundedFigure: int64;
begin
intRoundedFigure := round(dblFigure);
result := intRoundedFigure mod 65536;
end;
With the returned figure apply that to your gauge.
Hope this helps.
Cheers
Elliot