Did the FF update, iTunes update, hanging and backup issues start after the email or are these separate issues?
I'd say the chances of a virus are slim. You can try the online virus scanner from Symantec..
http://security.symantec.com/sscv6/home.asp?langid=ie&venid=sym&plfid=21&pkj=REMTPWFYJOKMFIDPMSV
As for anything else... I think you've done enough, unless you want to follow up with spybot or AdAware.
Try reinstalling iTunes. That should fix that problem as well. Settings should be fine.
You seem to be having a bit of a go with Win7. Sorry to always see these problems crop up.