I tried using the "Flash Splash1" button that someone had posted earlier and I almost **** myself. I think my phone tried to load the file I originally used to root it. I was getting really nervous so I pulled the battery and, to my relief, it powered on and it booted normally. I'm sure that method works but I'm scared of it now.
I tried the original instructions and it rebooted my phone before I was ready so I did this in the command prompt (this was mentioned on the first page of posts):
cd C:\android-sdk-windows\tools
adb shell
su
reboot bootloader
fastboot flash splash1 <copy and paste file name here>
fastboot reboot
Of course this will only work if you've downloaded the program, converted your picture and placed it in the tools directory of SDK.
Worked great for me. I couldn't be happier!