Afternoon Everyone,
Okay, well I've finally jailbroken my iPhone for the second time, after working out why Redsnow wouldn't recognise my iPhone firmware.
That's because, you have to:
1) Update iTunes to version 3.0.1, and use the firmware file called "
iPhone1.2_3.0.1_7A400_Restore", but then...
2) Once your iPhone's been reformatted and prepared by iTunes, use Redsnow to jailbreak it,
but get Redsnow to use firmware file "
iPhone1.2_3.0_A7341_Restore" instead!
Both ipsw files are 235mb in downloads!

So dial-up modem users, should forget this! (I had to use my local library's wireless internet service instead, to get them both.)
Basically, you can upgrade iTunes to 3.0.1, but then Redsnow will downgrade your iPhone partially, to 3.0, in order to Jailbrek it, but retaining all the 3.0.1 functionality!
Now, my 3G phone is all working good and proper, so is Cydia

, and I can now re-install all my Apps again, via iTunes, and re-enter all of my Contacts (which are currently written down on both sides of an A4 piece of paper)!
It's been a bit of a stressful few hours, as I thought I'd totally bricked my iPhone last night, but once I'd realised the problem (see the notes in 1 and 2 above), it all became clear!
Thanks to everyone in this thread, especially UEF, Gary D and Chelsea.Tone for their help, advice, wisdom, guidance... and more importantly, patience with me, in helping rectify this issue! Thanks folks!
Now, we return you all to your normal scheduled programming!
Pooch