Absolutely No Difference for Me
Hi:
I have both: BT built-in to my PB, and the D-Link USB dongle for my iMac G5. I use both with the Apple keyboard and mouse and I see absolutely no difference: both have no latency, always work and are a pleasure. I would go for either one, but I must admit that I would not like it if my PB had no internal BT: having the dongle hanging from the side with the tiny green light blinking would be a disappointment. On the back of the iMac however, it's a non-issue. Hope taht helps!