I have always used backup software - it's helped me out of difficulties so many times.  I've gone to using Acronis True Image Home 2009 on one of my computers today, upgrading from a previous version.  I'll see if it's worth doing the other computer after running a backup.

If you don't have backup software, you are asking for trouble.  You will need it in due course.  I've ordered a new hard drive and will restore to that when it arrives.  That will tell me if it's worth upgrading the laptop.