Almost $650. I took my time acquiring components and there were some great black Friday deals online that week last November. I got: e8400, GA-P35-DS3L MOBO, Corsair vx550 PSU, WD 640GB aaks HDD, 2GB cheap Corsair RAM, EVGA 192 core GTX 260, Samsung CD-R/DVD+/-R drive, Arctic Silver 5, a couple very good case fans, some hardware (screws, nuts, washers), and paint.
I re-used an old HDD, my trusty mouse and vintage IBM keyboard, monitor, and a 10-year-old case (which I modified for cooling and to fit the ginormous GTX 260). I later received a 20" Viewsonic VA2026w monitor as a gift to replace my 17" CRT, so I guess you could add maybe $225 to the cost? I know it was purchased at a discount, but I don't know how much.
With a mild overclock I am very happy with the speed. I have a nice gaming rig for a great price.
I fluctuate between major and minor upgrades depending on what is coming out in the near and distant future (in computer hardware terms) balanced with what I want now. This one was VERY major as I hadn't upgraded in a while. I will soon add a big HDD to replace my old IDE drive. Maybe more and better RAM and when I go from XP Pro to Windows 7 later this year, also. But past that is up in the air. Maybe a better GPU will be next. Then maybe a CPU/MOBO/RAM + whatever else I can't re-use when I decide what I want to do beyond LGA 775. The future will dictate my plans. I haven't looked that far ahead. I'll skip the current i7's, though.