How do I get a 2G really back to factory settings?

[Kraut55]

2G 8GB, 3.0

This is the iPhone on which I tested everything before the iPhones of the other family members were jailbroken, updated etc. It has been used with iBrickr, ZiPhone, Quickpwn. Files have been added/deleted with the iPhone-browser and WinSPC, it has seen green screens, red screens - in other words everything.
Today I just upgraded it to 3.0 and found out that I did not even have to use redsn0w. Everything still works and it has the new features. Go figure.
On the other hand there are always little things like: I use an application and it freezes when I try to do a certain thing. Or I try to delete an application and after I click on the x of the wiggling icon the delete screen comes up but is not touch sensitive anymore, the iPhone freezes.

So what I would like to do is get it back to its original stage, meaning that all the extra files that might have been added at some stage will be erase, that I have a clean slate from which I could update to 3.0, jailbreak etc.

I guess a normal update won't do that. What would I have to do?
Thank you.

[smirkis]

open itunes. and click restore lol

[Kraut55]

I am aware that iTunes has the Restore button but I wonder if it erases everything (and I mean e v e r y t h i n g) also in folders that I created or if it just replaces the OS files with the original ones from 1.1.2?

[Kraut55]

Got help in another forum. Consider thread closed.

[SharpieBandit]

You have to DFU and restore right? Just wondering.