I bought an Alienware at the end of 1998 that cost me $3600. Top of the line at the time with a 19" monitor. Didn't have any problems with it so I didn't have to use their tech support. Between late 98 and late 2001 I replaced every component in the machine except the cpu and mobo. In the end it's averaged out to a cost of ~$100/month for that machine. I still use the monitor, but passed the computer down to my bro and now have a machine 3x as fast at 1/3 the cost.
Alienware machines are great but expensive. Would I buy from them again? No, I'd build my own. Computers are really coming down in price to the point where they are looking more like appliances. You can get a decent machine for $1000 (no, not top of the line) and replace the video card with whatever you want.