No, that's not really a good deal. If you want to save then building your own computer is the way to go. Personally I think that...what that's like....$275-$300 US right? I don't think that just the case, mobo, and CPU is worth that much. I'm gonna assume the case comes with a power supply? If so you should look up the wattage and what kind of rails it has. Meaning the +3.3, +5, and +12 volt rails. see what their max Amperage is. a good +12v rail would be atleast 22a.
You can get a mobo for your needs for like $50-$75, you can get the 2500+ XP for like $85 I think it is and hell you could get a case like the ThermalTake Xasier III and that comes with a nice 420w PSU and that whole case with 4 fans, thermal probe, temp readings in the drive bay is $125, so with mobo, CPU, and CASE in that scenario runs you about $275 US which is about the same, but you are insured better quality parts.