ECC and Buffered (Registered) memory question ?????

How much slower will a system with 256 to 521MB ECC and buffered memory be compared to the same system with non-ECC and unbuffered (same CAS latency) be when:

1) Used for games.
2) Used for general office work.

I understand what ECC and buffered memory is and how it works but I don't know the speed implications.

You won't personally notice the speed difference when using it but it's about 5%-10% slower than unbuffered, depending on the system. Doesn't overclock very well either.