So I want to now whether these parts actually CAN go together because this is my first time and my bro did it so easily >.>. Trust me, he won't help me

. Also need to know whether my power supply is enough to run the computer and if XP is the way to go (i already have disk) and if I MIGHT need Vista ABSOLUTELY because I don't got that kind of cash. Here is a list of my hardware and their prices. Can you also let me know if I am getting ripped off? Plan of purchase: newegg.com.
Case:$45 - Rosewill R5604-TBK 0.8mm Japanese Cold Rolled Steel Screw-less Dual 120mm Fans ATX Mid Tower Computer Case - Retail
*Raw*Proccessor:$50 - AMD Athlon X2 7550 Kuma 2.5GHz Socket AM2+ 95W Dual-Core Processor Model AD7550WCJ2BGH - OEM
RAM:$47 - G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model F2-6400CL5D-4GBPQ - Retail
ROM:$73 - Sony Optiarc Black 2X BD-ROM SATA Model BR-5100S - OEM
Sound:$16 - BYTECC BT-P8CHS PCI Interface 3D Sound Card - Retail
Card Reader:$35 - Silverstone FP35B USB 2.0 Card Reader with extra silver front panel - Retail
HDD:$40 - Western Digital Caviar SE WD1600AAJS 160GB 7200 RPM SATA 3.0Gb/s 3.5" Internal Hard Drive - OEM
Motherboard:$80 - ASUS M4A78 Plus ATX AMD Motherboard - Retail
Power:$50 - Rosewill RP500-2 500W ATX12V v2.01 Power Supply - Retail
Graphic Card:$70 - HIS Hightech H467QT512P Radeon HD 4670 IceQ Turbo 512MB 128-bit GDDR3 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Retail
---------------------CABLES-----------------------
SATA Cables:$3 - KINGWIN 15.74" SATA Data & Power combo cable Model SAC-04 - Retail
---------------------COOLING----------------------
Case Fan:$13.60 - Thermaltake A2018 Blue LED Case Fan - Retail
VGA Cooler:$8 - EVERCOOL VC-RE Ball All In One Vga Cooler Kit - Retail
Proccessor Fan:$10 - Rosewill RCX-Z80-AL 80mm Sleeve CPU Cooler - Retail
Thermal Paste:$9 - Arctic Silver 5 Thermal Compound - OEM
TOTAL: ~$550 w/o Shipping.