Jailbreak - keeping current data / setup

I'd love to jailbreak, just to get all the customization features, however I don't want to lose all my current data and setup (eg all the apps on my iPod, my mail accounts, etc, and game save data).

I believe that before you jailbreak, that you have to restore the original firmware - is this true? And if it is, can I make a backup before jailbreaking, restore the backup after jailbreaking, and still have both the jailbreak and setup at the same time?

Thanks!

EDIT: How can I do the restore once I've jailbroken without wiping the iPod again?

 

But I can just re-sync the music and videos on again, can't I?

I'm slightly (read: very) confused about this whole JB thing :s I want to jailbreak, but I don't want to lose all my data (email accounts, app info and game save data, for example). So, questions:

1) Do I need to restore my iPod to factory settings before jailbreaking?

2) If yes, can I restore my data from a backup without getting rid of the jailbreak?

3) If no, can I jailbreak my iPod as-is, because it's on 3.0 (using RedSn0w)?

4) Any other info?

Thanks in advance!

 

Brilliant, one other question: when I'm jailbreaking and it asks for the ISPW, do I give my latest backup, or the original 3.0 one?