Where is the PlatformSupport.plist file in the final version of Mac OS X Lion

Can't be done on a CoreDuo. You need a Core2Duo.

https://discussions.apple.com/docs/DOC-3261 says you probably are better off just upgrading to 10.6.8 and getting the latest Java, unless you don't use Java or have software that is only 10.6.7 compatible. To upgrade to Lion you also need to check all your software/hardware is compatible with it, using this link:

https://discussions.apple.com/docs/DOC-2465

OK, I stand corrected, though I haven't tried this myself. Backup your data at least twice in clone format before trying anything so risky:

https://discussions.apple.com/docs/DOC-1992

Be careful only to do this with either the App Store download file, and do not install that purchased copy on that machine, or the USB Flash key version of Lion. Do not attempt to download any DMG from this thread, as there is no guarantee it is safe for your computer, or that it will work with any of the security updates for your computer. Just follow the directions with the retail, since apparently it works with Gold Master. I would verify with the posters of this thread, before trying it:

http://www.insanelymac.com/forum/index.php?showtopic=249877

If that doesn't work, well you have good reason to buy a used or refurbished iMac Core 2 Duo, and use the installer on that instead, and just recover your backup you made for the CoreDuo before you did this. See my FAQ* on used and refurbished Macs:

http://www.macmaps.com/usedrefurbished.html

And remember, there are some who are unhappy with Lion, and need to keep a copy of 10.6.8 anyway, because you lose Rosetta with Lion.

* Links to my pages may give me compensation.