Looking to redo my computer

[Durftard]

I have a Dell E520 and I do a lot of gaming and it doesn't quite get the job done so I'm looking to totally redo my computer. I basically want to build a new computer and harvest some basic parts from the dell, eg. DVD Drives, Hard Drive, so I just wanted to know if everything would be compatible, I will list the parts below and if you could tell me if it would work as a new pc that would be great.

1. 250 GB Sata Hard Drive - Already in my dell.
2. Phillips DVD-Rom Drive - Already in my dell.
3. GIGABYTE GA-73PVM-S2H LGA 775 NVIDIA GeForce 7100 HDMI Micro ATX Intel Motherboard Newegg.com - GIGABYTE GA-73PVM-S2H LGA 775 NVIDIA GeForce 7100 HDMI Micro ATX Intel Motherboard - Retail
4. RAIDMAX Smilodon Extreme Black ATX-612WEB SECC STEEL ATX Mid Tower Computer CaseNo Power Supply Newegg.com - RAIDMAX Smilodon Extreme Black ATX-612WEB SECC STEEL ATX Mid Tower Computer CaseNo Power Supply - Retail
5. Intel Core 2 Duo E4500 Allendale 2.2GHz 2M shared L2 Cache LGA 775 65W Dual-Core Processor Newegg.com - Intel Core 2 Duo E4500 Allendale 2.2GHz 2M shared L2 Cache LGA 775 65W Dual-Core Processor - Retail
6. EVGA 256-P3-N791-AR GeForce 8800GT 256MB 256-bit GDDR3 PCI Express 2.0 HDCP Ready SLI Supported Video Card Newegg.com - EVGA 256-P3-N791-AR GeForce 8800GT 256MB 256-bit GDDR3 PCI Express 2.0 HDCP Ready SLI Supported Video Card - Retail
7. Rosewill RP500 ATX12V v1.3/ EPS12V 500W Power Supply 115/230 V CSA, CB, TUV, FCC, UL - Retail Newegg.com - Rosewill RP500 ATX12V v1.3/ EPS12V 500W Power Supply 115/230 V CSA, CB, TUV, FCC, UL - Retail

Use the motherboard peterhuang suggested.
Use the RAM BiGyLiLuPdAmIdL suggested. (or Newegg.com - Crucial Ballistix 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory - Retail - $50 after rebate)
Keep your current PSU.
Keep your current CPU.

With the extra money you can...

add Newegg.com - ARCTIC COOLING Freezer 7 Pro 92mm CPU Cooler - Retail (+$22)
upgrade to ClubIT Product - GIGABYTE Geforce 8800GT 512MB 256bit GDDR3 PCI-Express 2.0 HDCP & SLI Ready Video Card Retail GV-NX88T512H-B (+$35)
upgrade to Newegg.com - EVGA 512-P3-N841-A3 GeForce 8800GTS (G92) 512MB 256-bit GDDR3 PCI Express 2.0 HDCP Ready SLI Supported Video Card - Retail (+$145)

or maybe upgrade the case?
newegg has a great deal on the cooler master stacker right now, $110 after rebate
Newegg.com - COOLER MASTER Stacker 830 RC-830-SSN2-GP Silver Aluminum ATX Full Tower Computer Case - Retail
heres another great case, $80 after rebate
Newegg.com - Antec Nine Hundred Black Steel ATX Mid Tower Computer Case - Retail


personally, i'd suggest the AF7 + 8800GT 512MB + Antec 900