Question: How to force to use Multi-Kernel processor to work at 90%?

I've bought a new computer recently and was disappointed, because Maple uses only 25% of that processor (my old computer used 99% of CPU).

I have Intel Core i5 750 processor (it has 4 kernels).
From the Screenshot you can see that It uses only 25%, but not because it uses only one kernel (it uses all 4 kernels).

If I open two Maple instances and run the same program on all of them at once then I get 50% of CPU used.

The question is:
how to force to use Multi-Kernel processor to work at 90% (if needed) with one single Maple program?

It seems that this isn't a limitation to Maple, but for all other programs as well.
For example, open Notepad and put this text there:

Option Explicit
Dim i
For i = 1 to 10^8
Next
Wscript.Echo "i = " & i

Save it as exampe.txt and then rename it to exampe.vbs
Then double-click it to run.

It will also use only 25% of CPU (if you have a processor with 4 kernels).

I've made those tests on WinXp+SP2, but my friend told me that on Windows 7 Ultimate he got similar result.