Apple Can I *restore* iPod Touch to a previous firmware?

[AC/DS]

Just as I was reading the Complete iOS Jailbreak Guide where it says in "important post-jailbreak info" about restoring from an IPSW file a probably stupid question occurred to me... Does this mean that I can restore my iPod Touch to the firmware of my choice?
I recently updated from 4.1 to 4.2.1, and as it seems only a tethered JB is available for this version, could I restore the iPod back to 4.1. and then happily do the untethered JB via Greenpois0n?
Would my device (with 4.1) be completely the same as it was before I updated to 4.2.1? Thanks for any input.

 

[Sebbel]

Yes, you can restore it. But only when you have the SHSH Blobs for the firmware you want to downgrade to. You wonder what SHSH Blobs are and if you have them? just go to cydia and look at the main page, there is written: SHSH: iOS (for me) 3.1.3, 4.0, 4.0.2, 4.1
So, if there stands the firmware you want to downgrade to, you can.

How to restore?
Well, I just can tell about how to do it with windows, so if you have a mac, you have to google your way around.
How to do it on windows: Go to your hosts file in this directory: \Windows\System32\drivers\etc
Open it and just add this line under the other lines: 74.208.10.249 gs.apple.com

Before continuing enter restore mode. One way to do this is disconnect your ipod from the computer and turn your ipod off. Start iTunes. Hold the home button on your ipod and plug it in. Continue holding the home button until iTunes indicates you are in restore mode.

After this you have to download the firmware you want to restore to. just google it.
When you got the firmware, go into itunes and hold shift and click on Restore.
There should be opening a window where you can choose the firmware you downloaded earlier. Select it and click restore. After that, just wait for the firmware installing and after a reboot you should be on your firmware!

 

[metamaster]

You can also do the above with Tiny Umbrella. It patches the hosts files automatically and saves your SHSH Blobs. To downgrade, start the TSS server, shift-press restore in iTunes and select the desired firmware.

 

[AC/DS]

Amazing, thanks. There are very knowledgeable people around here.
I won't ask any more noobish questions, hopefully.

 

[AC/DS]

*BUMP*
This is for anybody trying to downgrade from 4.2.1 to 4.1.
My experience is that it's not worth it. The reason being, when you back up your device (apps and everything) you have 4.2.1 in it, but when you want to RESTORE that data you have 4.1 because you have downgraded, and iTunes WILL NOT LET YOU restore your own backup.
It will permanently bug you with a message that "this device cannot be restored because the data is from older firmware version" (or something to that effect).
Even after I digged out some info on the net on how to remedy this problem (you have to manually change some text document in the iTunes backup folder), iTunes STILL would not let me restore my data.
So I switched back to 4.2.1, disgusted.
This is just my experience, if there are any gurus around who can show me what I did wrong, please do so.
I am just a beginner, learning on my own mistakes.

EDIT: Also, isn't multitasking improved in 4.2.1? I recall hearing or reading it somewhere... If it is, then it's really better to use 4.2.1 and wait for an untethered jailbreak. IMHO.

 

[metamaster]

^ Weird... In downgraded my iPad a bunch of times and the backups worked (not from 4.2.1). Maybe it's only for 4.2.1. It might add something that 4.1 doesn't support.