Yeah, newegg is great about returns. I tried the Buffalo 3200 first to see how it was and wasn't entirely pleased with it, as I could not run as agressive as settings as I wanted at 380MHz. Given that it represented as 400MHz ram, I called newegg and they gave me an RMA immediately and did not charge me a restocking fee. Given that you can ship a couple sticks of ram via USPS for next to nothing you risk little by giving it a shot.
I bought the 3700 from newegg and I like it better. It definitely tolerates more agressive settings and is a great value. I can recommend the 3700 to all, and the 3200 to anyone who is not running an Intel dual channel chipset. Your KT266a should have no compatibility issues and perform excellently with either type.