I suggest to install Snow 10.6.8 and do all the securitiy updates for this system.
Lion is a resource eater and therefore slower. I had it on my MBP with Core 2 Duo, before it died the nvidia gfx dead.
Upgrade Ram 4 GB seems to be usefull.
Get an original 10 6.? (don't no the which version was the last complete release) and download the necessary comboupdates to upgrade to 10 6.8.
Here in the Downloads get Pandora. You are guided with tips throu the pre- and postinstall.
With the search funktion you can surely find many topics with similar builds.
Have fun.Go to the full post