what wont let it update? is itunes giving an error code? will the install not download?
google my friend "itunes error 3194"
and you'll find a bunch of links to help you out. in a nutshell, looks like someone used tinyumbrella to save the SHSH blobs in preparation for a jailbreak. just follow the steps on any of the websites to correct this.
you need to download and install TinyUmbrella and run the program while ensuring you have unchecked 'Set Hosts to Cydia on Exit'. Instructions here: