trouble with path to swt dll

[Tim McGuire]

When does Eclipse recognize a change in the PATH system variable?
I created a HelloWorld class that uses SWT.
The manual says there are several ways to get my class to recognize the SWT DLL. One is to set it as an argument in the run configuration under VM Arguments. The argument I used is
-Djava.library.path="C:\Program Files\eclipse\plugins\org.eclipse.swt.win32_2.1.1\os\win32\x86"
and it works great.
I can also append the location of this library to my PATH variable:
C:\Program Files\eclipse\plugins\org.eclipse.swt.win32_2.1.1\os\win32\x86
or:
C:\PROGRA~1\eclipse\plugins\org.eclipse.swt.win32_2.1.1\os\win32\x86
but it could not find the library it needed. Then, I restarted Eclipse and it worked. But THEN, I tried breaking the PATH variable to see if I could break it again and now it won't break even if I restart Eclipse. So, what gives? Is there a way inside eclipse to make it recognize changes to an environment variable? Why won't it break now that the PATH variable is wrong?
Thanks!