It's become en vogue in the last part of the 20th century to tear down the myths of the founding fathers. I think that now every college freshman who protests the WTO knows that Thomas Jefferson owned slaves and is rumored to have fathered an illegitimate child with Sally Hemmings.
To be sure, Thomas Jefferson was a man of his times as much as he was an enlightened agrarian philosopher.
His views on slavery were mixed, he felt that it was at once the greatest evil in the world but at least subconsciously acknowledged that his life of learning and agriculture would have been impossible if not for the cheap (free) labor of the slaves. Giant country estates growing tobacco and other crops do take a lot of work after all, and a farmer that does all that work can't very well be a Virginia gentleman and scholar due to time constraints.
I don't want you to think that Jefferson's conflicted views on slavery came from his view of the African slaves as his fellow man though. In his 'Notes on the state of Virginia'- he makes it clear that he doesn't view them as intellectual equals and explains that they need 'guidance'.
It's too hard to psycho analyze Jefferson's racial views in one blog post, this subject could fill books, but it's interesting that as he grew older, he grew more depressed when he came to the understanding that Southern slavery, not Northern anger over the embargoes against commerce with Europe were going to tear the country apart.