It's been awhile since I've checked up on bitcoin. I saw that the price has risen greatly and I want to sell my coins.  I have a good majority of my coins backed up in my old wallet.dat file.... but I am missing roughly 80 bitcoins.

I believe I purchased them and left them on the TradeHill.com website without transferring them to my wallet, but I cannot seem to connect- I guess it went down?

Is there any way to retrieve my coins? Am I out of luck?

Also, where is the best / safest / easiest place to sell the rest of my coins? mtgox.com?

Help!
Thanks!