Hi,
I have a compaq dx2450 / AMD Phenom x3 8600B
Until a month ago I only had 4GB ram, believing this to be the max -- but it turns out 8GB is working rather nicely with Windows 8.1 meaning it's still quite a viable system for general desktop use.
Out of interest are there any viable cpu alternatives beyond the 8600B. I know it's an AM2 processor, but no idea what the BIOS supports (5.63). I'd guess that's the limiting factor - other than cost effectiveness.
I may upgrade at some point - lightroom/photo editing being the main issue ....