Using the newest Classapth with gcj ?

Hi,

I have a java (1.5) project running in Eclipse currently using Sun's
compiler and wanted to use gcj instead. So I've been trying to use
Eclipse + java-1.5.0-gcj-4.3-1.5.0.0 (just downloaded the standard
package from the repository of Ubuntu 8.04 LTS)

It didn't compile properly at first giving me errors related to awt/swing...

As often the case, the repositories are sometimes not so uptodate with
the latest development, so I checked the gcj website and then I
realised that the libgcj project has been stopped, or better, merged
with the Classpath project which then provides the java libraries.
That means that libgcj library provided in Ubuntu's latest repository
is relatively old, so If I wanted to have the latest java libraries, I
would have to get the latest Classpath, is that right ?

I did download the latest development Classpath  and run the typical
configure + make + make install, but I'm not sure what this has given
me! How do I get gcj to use this newly installed Classpath library
instead of libgcj ?

and how to get this bundled correctly with Eclipse ? Do I have to
rebuild a new JRE to be used with Eclipse?
Sorry if this a daft question but I cannot find any real useful info
and I'm quite confused about JRE, JDK, gcj, libgcj, classpath how they
all fit (or not!) together


Cheers
David