You should have a look at Acronis software, it is an image back up to an external drive.
If you ever run into a problem, just reinstall from the back up and everything is put back the way it was when you last backed up.
It's inexpensive and easy to use. I had an HD failure on a Dell laptop, went to Fry's for a new one and had the machine back up in an hour or so, OS, programs, everything.
For me it was a life saver as I have a business I run from my house so the data on my drive is very important, I highly recommend it
If I need to restore, I run CloneGenius DVD. It restores the OS partition to the last backup.
CG has saved me several times. It takes about 40 minutes to create the OS partition backup (28 gb) and about the same about of time to restore. That sure beats having to reinstall Windows and programs from scratch.
It is now called Partition Genius.