I don't think I made myself clear. According to CSI, the next solver of ETABS 10 will NOT support multiple processors as it will not be a multi-threaded application. 64 bit OS and CPU's will be supported however.
There is NO benefit whatsoever of purchasing multiple processor computers for running ETABS, unless you have several buildings which you want to run simultaneously... The current fastest chip out there is the Core 2 Duo Extreme. Even though you will not be using the second core (except if you want to do something else while the program runs) it is probably the fastest processor capable of running single threaded apps such as ETABS.
It can also be overclocked quite a bit. The best place to learn about all this is in the gaming forums. In other words, if you are looking for the ultimate computer to run ETABS look no further than extreme gaming rigs... Depending in your taste (and age) they tend to look pretty cool as well....
Regards,
Luis