Think about it... 10 years from now people will be laughing at our 2ghz proc's... and the idea of quantum computing may come true in that short amount of time.
"Why do we need a 2ghz processor when it performs like a 1.4ghz in reality?"
AMD has a processor rating on all models; for example, an AMD Athlon XP 2000+ running at 1.67ghz can compete with a P4 2.0ghz. The focus is of the QuantiSpeed architecture of the processor; which allows higher performance through chip architecture rather than clock speed.
Answer to question 2:
Intel Itanium / Itanium 2 (scheduled to be released); as an example; but they never really caught on in the server market.
Also, Sun has been making 64-bit processors for years. Doubt this is really what you meant when saying something bout this though. All of the Sparcs/Sun Workstations/Sun Servers, etc. run 64-bit Risc based processors.
As for 1ghz/2ghz being obsolute, when did my 200mzh and 350mzh go out of style? I have never owned anything faster then either of thoughs and really have never needed to either. Everything I wanted to do I did in Linux or it wasn't a high-end game. Everything else that is CPU intensive (like DVD ripping, web server, compiling) just takes longer, and that isn't really a big deal to me either. Hell, I just upgraded my 2x burner to a 24x. Bought the 2x back in '95 when they first came out for around $250. hehe...goes to show how much stuff changes in so little time.