Molyy said:
So I guess I'd better do a backup before upgrading. But since you said that all the files will be retained, what exactly do I need to backup? Files and applications on the C drive?
BTW, I'm choosing between some free backup software, such as easeus todo backup, FBackup, and acebackup.
Anyone has any experience with these freeware?
Try Macrium Reflect free version. http://www.macrium.com/reflectfree.aspx

I believe this will create an image of your system which can be restored.