The old E521 upgrades (in 2011)

Hello all... I've had an E521 since 2005 and it's still running strong.  Since it is 2011... how have those upgrades to your E521 worked for you?  There may not be too many of us left.....  I've been very happy with it.  My current configuration is the 3800+ CPU and 4GB RAM.  

I would like to now upgrade to the 6000+ CPU as well as RAM (if possible).  I've read extensively and see that my chances of the 6000+ CPU working are pretty good, provided I use the correct wattage.  OK - no problem there.  Has anyone tried to upgrade past 4GB RAM? - possibly to 8, 12 or 16GB?  I'm not running this as a server but since memory is always getting cheaper (as well as the older CPUs), the prospects look better and better.

Thanks and I'm very curious to see what's happened out there to this PC! :emotion-1: