This is how i found to fix the no USB issue when updating to OSX 10.6.5.
1. download the OSX 10.6.4 combo update.
2. download Pacifist
3. download kext helper b7
4. Open The OSX 10.6.4 combo update with Pacifist
5. drag over the following files to the desktop, AppleUSBAudio.kext, AppleUSBMultitouch.kext, AppleUSBTopCase.kext, IOUSBFamily.kext, IOUSBMassStorageClass.kext, AppleUSBDisplays.kext.
I know you probably dont need all of these, but i downgraded all of these kexts and all seems to work fine.
6. open up Kext Helper b7 and drag all kext into the app, put in your password, all should be good.
7. reboot.
hope this works for everyone!! did for me.
happy dayz!!