I was just reading the comments at www.hacktheiphone.com and Mark there suggests that if you have hardware unlocked your phone you should restore using iTunes 7.3 and then install 7.4 and then go through the hardware unlock again using the updated tools such as iNdependence and AppInstaller.

I dont see the reason for it? can someone explain why you would do this?

Here is the link where he suggests this process:

http://www.hacktheiphone.com/iphone_information.html