Copy out the folder named "Mobile Applications". That's where the apps are located in. But to be sure, make a carbon copy of your "iTunes" folder entirely, that folder also contain the "iTunes Library" file and its corresponding XML equivalent. You need those two files to recover properly when you recover your iTunes back.

Another way of doing it is using a backup app for Windows. I dont know of any, so I could not comment on that. Backup the entire "iTunes" folder and keep it somewhere safe. Restore it back once you have recovered.

On a Mac it is easy. Turn on Time Machine, and it does the backing up automatically. If the event of a Mac crashing (very unlikely), it restores from the Time Machine with a single click, and you basically just relax and watch it does its magic.

What the TS wants is to back up the entire Library of his iTunes, including his apps. What you're backing up is your iPhone or your iPod Touch, into its backup repository within the iTunes folder. What further compounds his dilemma is the fact that he is using Windows, and as customary to those using Windows, a reformat is REQUIRED to keep the system running tip top. He does not want to have to totally wipe out his HDD and redownload the apps from iTunes again, he just want to back up his apps away from the HDD that is about to be wiped out from his reformat and reinsert it back after the reformat is done.

That is not correct. If you read the support KBs from Apple, you can even backup to you iPods, in this case, the iPod Classic, since it carries a hefty storage space. Otherwise, just grab an external HDD, and copy out your iTunes folder generally, or "Mobile Applications" folder specifically, if you're talking about the apps.