Netkas method of updating to 10 5 5
I am happy to say my mini booted up just fine and 10.7.5 is working well so far.
Only complaint so far is the lack of scroll arrows in Lion.
I also found a non working 2006 1.5Ghz Core Solo that needed some TLC and would not power up.
Turns out it had been opened up several times before and had hardware that was not seated correctly.
Since this worked, I went ahead and installed the 10.7.5 combo update.
This updated restored the platformsupport.plist, but I was able to remove it before restarting the mini.
The early Intel-based i Macs also had a socketed CPU and there are a couple C2D CPU upgrade reports here on those.) This page has pre-2009 model Mac Mini owner comments on Core 2 Duo (and some Core Duo) CPU upgrades as the (2006-2008 mfg) Intel-CPU Mac Mini has a CPU socket on the logic board (as did early Intel-based i Macs).
(And over time, CPU Prices drop as intel releases faster/later models.) For owners that swapped in a Core 2 Duo CPU, the original tip for Lion dev previews is reported to still work - I. Install lion on a drive connected to a supported mac (Target Disk Mode, FW, etc) and then delete the (hidden) "/System/Library/Core Services/Platform Support.plist" file.
The Lion volume should then work with the Core2Duo updated Mini (or i Mac).
If there's an easier way (installer check edit, etc) send a note. (Several reports below have notes on OS X Lion with C2D updated 2006-08 Minis.
The pins released easily (Unlike my 1.66 Core Duo).
I had a broken macbook with 2GB of memory laying around and installed it in this mini.
I then used the external drive to boot the mini with 10.7.5, formatted the internal hard drive and cloned 10.7.4 onto the internal drive and rebooted.