i second that ^^^^
Quad is a dream machine and if u have the money it's a great machine to buy.
Everything it has is really ahead of its time and there's plenty of room to expand for the next 4 years.
The only things it could have done better maybe a newer type of SATA connection + room for additional optical drive.
Also, as long as Apple don't declare PowerPC "RIP" and release a version Mac OS X in 2010 which only run on Intel machines, the Quad you're going to buy today will still powerful enough to run most applications of that time.