You either must erase your hard drive, or buy 10.6.3 retail, and apply the 10.6.6, 10.6.7 or 10.6.8 combo update for the flash drive to work. Either way cloning your machine twice, detaching all hardware except Apple wired keyboard, mouse, and a display when the machine is off, and upgrading all your applications and drivers for Lion compatibility on the clones is recommended. You can't use the 10.6 discs from another Mac.
The two others I use that are PowerPC applications are AppleWorks and Eric's Ultimate Solitaire (in addition to Quicken 2007).
I can't upgrade to Lion without Quicken at the least, and replacing AppleWorks would be an ugly chore for me.
I've been looking for a substitute solitaire game, but have not found one as elegant as Ultimate.
The press release link no longer takes you to anything pertaining to Lion.
You may want to change the link to the press release library page:
or even the specific press release on Lion: