Hard Drive: As long as its SATA (whether its SATA150 or SATA300 doesnt matter at all), and made by Western Digital or Seagate, you're sorted.
CD Drive: Make sure they are CD-Rewritable and DVD-Rewritable. Just choose two at the store, doesnt really matter.
Case: Well, you want a MID tower case. Not MINI, or FULL. Mini is too small, and full tower cases are, well, tall, and only needed when you have a gazillion drives.
The case must also be ATX-compatible. The big names here are Lian Li, Thermaltake and Cooler Master. You're looking for:
A 12cm fan grill at back of case.
Some sort of intake at the front of the case (preferably near the bottom).
A side fan grill in one of two places (this
case has a fan at both of these places); the top grill aids CPU cooling; the lower grill aids GPU cooling.
What you choose for the above 3 is down to you.
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You might want to upgrade to an E6400 (2.13GHz). You dont need to, but its up to you, and how much Fry's will charge you for this.