Almost never. Building your own would be the way to go but if you're deadset against it try here
Yes, Conroe is expected to ship June 23rd but face it - AMD's answer will be 2-3 months after that and so on. You just have to jump in at some point. That said, I would give it about three weeks to see if the Conroe causes AMD to price cut.
If you build get the following:
AMD FX-60 (or X2 4400+ for 80% performance for 1/2 price)
GeForce 7900GT (Stay away from the GTX - seems to be some issues)
2GB CAS2-3-2-5 memory (Patroit, OCZ or Crucial Ballistix - check mobo compatibility at ASUS website)
Western Digital Raptor 74GB or 150GB HDD
550-600W power supply (don't skimp here)
You'll be very happy.
Or, do like I did for my wife's PC and just click the Buy Now button at Electra Computer.