Sorry haven't been able to get on and answer questions/suggestions about your problems - been busy with the family today.
.NET Framework is required if you didn't already have Kies installed - there are numerous posts about using kies properly, and this is one of the caveats of the program.
How I did it:
I was having error after error getting it installed - I ended up uninstalling the current version of Kies that I had installed (1.5.1 I believe) Some have had success getting Kies to do the internal update to 1.5.3 by running as Admin, but I did not..
So once I uninstalled Kies, I did go to Regedit and "find Kies" and removed all instances of "Kies" (note: you will also find "cookies" as well
)
I then used the provided URL in the OP to reinstall Kies 1.5.3. Once installed, I restarted the PC. I believe I opened Kies first before connecting the phone (I don't have Kies to Autostart either).. with the provided URL, I believe Kies asked me to update, I declined..
IMPORTANT - Before plugging in your phone, make sure you have "device connection guide" at the top
right corner - If you do not, you will receive the MSC Thunder error.
I then plugged the phone in and the dialog box came up with the firmware upgrade message.
If you are running Win7 you can try running as Admin or running in Windows Compatibility mode (XP Service Pack 2/3)
I do believe my original problem I had was having kies trying to do the internal update as it would not actually install the downloaded files.. I never had problems with Kies before running that internal update.. which is why I opted to find the 1.5.3 version for installation.
I too have a warranty phone coming in from ATT as I was extremely frustrated with the support from ATT and Samsung - ATT told me to call Samsung, and Samsung told me to call ATT - so after that, I called the warranty department and should have my phone tomorrow. I REALLY wish Samsung would have announced that the firmware upgrade would be available through Kies - but then again, Kies is not exactly official for North America yet is it? I guess it's just one of those things!