You should consider building one yourself. I'm in the process of building my own for about $500 (not including monitors and hd's, which I'll use from my old system), all top-quality components from Newegg. The thing is that by buying a good motherboard and case you can make sure your system is upgradable for years to come. This is my case, mb, processor, video card:
COOLER MASTER CAVALIER 3 CAV-T03-UW Silver Aluminum Bezel, SECC Chassis ATX Mid Tower Computer Case
http://tinyurl.com/ajgok
ASUS A8N-E Socket 939 NVIDIA nForce4 Ultra ATX AMD Motherboard
AMD Athlon 64 3200+ Venice 1GHz FSB 512KB L2 Cache Socket 939 Processor
JATON Video-PX6600LE-256 Geforce 6600LE 256MB 128-bit DDR PCI Express x16 Video Card
The ASUS 939 mb will take the higher-end Athlon processors (currently going for around a grand) and 4 gig of memory. The case is large and well-ventilated, and I'm putting in an Antec 500w power supply, so I'm sitting pretty for a several years at least as far as upgrades.
Building a system is not nearly as difficult as you might think. Good components should have good manuals. A few screws for the ps, a few screws for the mb, plug in processor and memory, attach cables, install cards and drives, install software - bing bang boom, you gotta computer that'll last you for years. Something to consider, rather than paying $1200 for something that may not be as upgradable.
Harold