even if you're not going to actually build it yourself, i agree with the above sentiment by x030rxm...having a PC with "standard" components and not proprietary casing, cabling, etc. will serve you much better in the long run (greater expandability, most likely better quality components, etc.)..
you could take a look at companies like Velocity Micro (now selling in Best Buys), Cyber Power, etc. or, for more money, companies like Voodoo PC, Falcon Northwest, etc.
Monarch is definitely a good choice - pick your own parts and they'll compatibility/stress test everything and provide annual customer support for an additional fee...