I've used both, along with Ulead. My preference is for Adobe. Pinnacle had a number of items in the menu that required additional payment to activate. I felt that I was using a piece of shareware with nag screens rather than the expensive piece of software I thought I had purchased.

Adobe has given me fewer crashes, is better coordinated with Photoshop, has better chromakey results, and is (in my opinion) easier to use. I've used many of the advanced editing features and found them better accessed than Pinnacle. Try to get a deal on the bundle with photoshop elements if you don't have that yet. The biggest drawback to Adobe is the extensive menu system, it can be difficult to find what you need if you're not using it frequently and the screen is busier than Pinnacle.

If you're just doing simple movie editing try using the Windows Movie Maker editor that comes with XP. It's simple, but fine for making a quick movie edit. Best of all it's free.