Alan,

Welcome to the genalogy addiction, it goes very well with the kilt addiction.

Most of the people who emigrated to the Philadelphia/Lancaster PA are were Scots Irish from Northen Ireland who went to Ireland from Scotland during the Highland Clearances of the early 1700's. They migrated down the "Great Wagon Trail" from Pennslyvania to the Carolinas, Virginia, Georgia, Kentucky and Tennessee.

As Rex notes www.rootsweb.com is also a gold mine of information. There is a lot of misinformation and just plain blantant errors out there on the web, look for the well documented sources of information and also at the personal page for each of your ancestors.

Happy hunting, it's great fun.