I've been meaning to revisit this for awhile now.
I was able to find something that worked for me. It was from [cough] Microsoft [/cough]. It's called SyncToy.
PC Magazine had it listed in their Best Free Software article earlier this year. I'm using version 1, but it has been upgraded to version 2. The software is nothing fancy, you just set up two folders to sync, and pick the type of sync you want, and that's it.
One caution: deleting or moving a folder can have disastrous consequences. Make sure you're careful, or you could inadvertently wipe out a ton of stuff. I always use the preview button, just to make sure of what I'm doing before I hit the final sync.
I mostly use it to sync specific work files to my thumbdrive, and sync that thumbdrive again on the home computer. That's what I was looking for, and SyncToy has worked great for that.
SyncToy is available for free from Microsoft.