There seems to be a lot of new builders as of late. Here's what I suggest for a case. It really depend on how fast you like your PC to be. High performance machines need a good case that have adequate cooling. Most expensive or high end cases range from $70 on up. They provide support for bigger fans including a front fan, side fan, and rear exhaust fans. Some cases offer a top fan too, which is nice to have but not required. Some offer side air duct, again, not required but nice to have. Cheaper cases like the $30-$50ish cases are not too bad. They provide adequate cooling but generally uses smaller fans and don't have front fan support.
Here's the specs I did for another member here in this forum:
ABIT AN8-ULTRA Socket 939 NVIDIA nForce4 Ultra ATX AMD Motherboard - Retail
http://www.newegg.com/Product/Produ...N82E16813127212
This is a basic dual core CPU, but depending on how much you can afford, you can always bump this up to a 4400+ X2:
AMD Athlon 64 X2 3800+ 1GHz FSB 2 x 512KB L2 Cache Socket 939 Dual Core Processor - Retai
http://www.newegg.com/Product/Produ...N82E16819103562
OCZ Gold Series 1GB (2 x 512MB) 184-Pin DDR SDRAM Unbuffered DDR 400 (PC 3200) Dual Channel Kit System Memory - Retai
http://www.newegg.com/Product/Produ...N82E16820227211
Western Digital Raptor WD740GD 74GB 10,000 RPM 8MB Cache Serial ATA150 Hard Drive - OEM
http://www.newegg.com/Product/Produ...N82E16822144160
LITE-ON Beige 16X DVD+R 8X DVD+RW 4X DVD+R DL 16X DVD-R 6X DVD-RW 16X DVD-ROM 48X CD-R 24X CD-RW 48X CD-ROM 2M Cache IDE DVD Burner - OEM
http://www.newegg.com/Product/Produ...N82E16827106990
Antec SUPER LANBOY Silver anodized aluminum ATX Mini Tower Computer Case - Retail
http://www.newegg.com/Product/Produ...N82E16811129145
or
Thermaltake VB1000SNS Silver Steel/Plastic ATX Mid Tower Computer Case - Retail
http://www.newegg.com/Product/Product.asp?Item=N82E16811133148
Antec SmartPower 2.0 SP-500 ATX12V 500W Power Supply 100Vac to 240Vac +/- 10% TUV, UL, CUL, CE, CB, FCC - Retail
http://www.newegg.com/Product/Produ...N82E16817103937
eVGA 256-P2-N515-AX Geforce 7800GT 256MB 256-bit GDDR3 VIVO PCI Express x16 Desktop PC - Retail
http://www.newegg.com/Product/Produ...N82E16814130247