I had tried there, no luck they are not the right drivers for the RNX-G300E, note theres no LX or EX involved. There site lists this card under discontinued items. My son Phil was able to find (and get) the the drivers on Rosewill by going through microsoft.com and coming in the back door and found them.
I know its an enexpensive card but...... I downloaded the ver 1.0 for XP and it works great. I will try and put the link below. if not just cut and paste. "All hail the Phil"