I asked the same question, at some length, with a Quicken chat today. The Quicken representative assured me that all of the same investment tracking functionality that existed in '07 Quicken Deluxe was in the '10 Deluxe. I ordered the update, and we'll see.
Beware! I just upgraded from 2007 Deluxe to 2010 Deluxe and lost 2 years of data (from 2008 on). Saw on a support forum that someone else had the same problem - so far no fix. Intuit is blaming it on a corrupt data file when it's clearly a conversion bug. Customer support told me I would have to re-enter the data by hand. Even going back to Quicken 2007 didn't solve the problem until I cleansed my system completely and started over. What a nightmare!