I agree with utilizing hardware till it's old and crappy. I haven't posted pics of it yet on the forum, but I rebuilt an old HP xw8600 workstation into a larger case for my FreeNAS build. It was interesting to say the least, as it's fun to see how the proprietary connections that HP uses made me have to MacGuyver a few of the connections to get everything to work. When I got it, it had a single x5460 Xeon in it, and I went on eBay and picked up a second one. Bumped it's RAM up to 16GB and modified the case to take a five slot drivebay. It's def a Frankenstein to say the least... absolutely not power efficient, as it sits around 280W at idle haha...
But it works for me, the ROI of spending the $$ to build a new one doesn't make sense for now. I'm just going to run it till the PSU dies and then build something else out of another used Xeon based box. =D