The iPhone and iPod Touch are fairly immune from Viruses and Malware at present!!! As far as I am aware there are NO viruses and malware for the iTouch in existence. That is not to say that someone won't develop one but the iTouch and iPhone run a locked-down version of OSX which in itself has almost no recorded viruses and malware .. the prospects are good for the moment.
So .. no need to worry for the time being. Windows viruses and malware either in a website or an email or file cannot affect the iTouch.
There are NO anti-virus or anti-malware software products for the iTouch in any case, so until something appears there's nothing you can do in any case.