Build it from scratch.
Do not get a GTS250 or a 1TB hard disk.
Look toward the future, so get a GTX 560 or even 2x GTX460's
Power Supply, get a 800+W Modular PSU, preferably, Corsair, Cooler Master or Thermaltake.
Motherboard: Gigabyte, Asus, MSI are good brands. (DDR3, SATA3 etc.)
Processor: Intel (nothing else matters, don't let others fool you >.>)
Memory: G.Skill, Corsair, Kingston are all good brands.
Case: Get a nice sturdy case that you like and then link it here and we'll tell you if it's good.
Hard drive (OS): Get an SSD or the OS and for the main programs and maybe 1 or 2 games you plan to play alot.
Hard drive (storage): Get at max a 500GB or get 2x 500GB and run it in RAID. I don't recommend getting any single drive over 640GB though.
