Incremental backup software

A friend of mine just got an external USB drive and the software that came with it is OK for back ups, not great, but it does the job and is easy to use. But the things is, it doesn't do incremental back ups. In other words, lets say you have a folder called 'data'. Not too original, but whatever. Lets say inside this folder you have some Excel sheets, some Word docs, etc. Lets say you make some changes to one or two Excel sheets, and you add a new paragraph to a Word document. When you go to back up with the included software it will back up the entire 'Data' folder each time you click 'BackUp Now'. Yeah, it's thorough, but it also seems to be a waste of space. After 5 back up sessions you have 5 folders called 'Data-%the date and time%' instead of it check the folders already backed up and only updating what has changed. So, does anybody know of an EASY to use back up app? Basically it should have a button to Add files/folders, a button to Remove files/folders, a button to select a target back up location, and a 'Back Up Now' button. That's it. No fancy scheduling or anything like that.....

Thanks!

 

Ahhh.... Sync Toy..... Now why couldn't I rememder that? I've heard of SyncToy and I think I've even used it a few times.... thanks for jogging my swiss cheese memory