As many of you are aware although the backup in Windows Vista was easy to use - it had no control over exactly what you wanted backup. The only controls were things like pictures, documents, recorded TV etc, and of course if you've got lots of php files and things like that in your documents folder you had to select the other files option, which would pretty much backup everything on the system - resulting in extremely large backup files.
Using NT Backup on older systems my backups would work out at about 15GB, with Windows Vista 60 or 70GB wouldn't be uncommon, times that by 3 machines and that soon fills your hard disks. Luckily I didn't have to put up with this for very long, as Windows Home Server came out in the same year which handles backups brilliantly.
In Windows 7 however the team responsible for backup have clearly listened to feedback and added much more control back over backup, without making it too complicated for people to actually use.
Then if you want more control over it you can, by including or excluding locations and specific file types.