The Application Support Disk allows you to:-
- rebuild start file
- rebuild system and driver files
- return to shipping status (puts it back to how it was when you got it including all the preinstalled software you probably never use much of)
However to do his I think you should have two more partitions on the drive "Tools and Recovery"
Best option is what you have already done in installing W7 - then set up your broad band and e-mail add all you security programs and what ever programs you generally use.
When the machine is as you want it then use the backup facility in W7 to make an image onto DVDs or an external drive so you can get back to that if you need it.