Single Certified Ram
Single Certified Ram
Are all these computer parts compatable with eachother?
LIST OF COMPUTER SUPPLIES TO BUILD A CP
CPU 
$60)AMD Athlon II X2 250 Regor 3.0GHz 2 x 1MB L2 Cache Socket AM3 65W Dual-Core Desktop Processor
HARD DRIVE $45)Western Digital Caviar Blue WD2500AAJS 250GB 7200 RPM 8MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive
MOTHERBOARD:($80)Western Digital Caviar Blue WD2500AAJS 250GB 7200 RPM 8MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive
RAM(MORE) $45/2)CORSAIR 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333 Desktop Memory
POWER SUP. $45)Rosewill Green Series RG430-S12 430W Continuous @40°C, 80 PLUS Certified, Single 12V Rail, Active PFC "Compatible with Core i7,i5" Power Supply
CD DRIVE $20)LITE-ON Black 24X DVD+R 8X DVD+RW 8X DVD+R DL 24X DVD-R 6X DVD-RW 12X DVD-RAM
OPTIONAL
GRAPHICS
CARD
UPGRADE $120)GIGABYTE GV-N450OC-1GI GeForce GTS 450 (Fermi) 1GB 128-bit GDDR5 PCI Express 2.0 x16 HDCP Ready SLI Support Video Card
MOTHERBOARD : GIGABYTE GA-MA770T-UD3 AM3 AMD 770 ATX AMD Motherboard
Can't say for sure since you didn't say what motherboard you have, so I can't tell if the RAM will work with it.
Other than that, the power supply is a little weak and should be replaced if you have any intention of going for the graphics card and/or playing modern games.
You will also need an x64 operating system in order to take advantage of the 4GB of RAM.
Thanks for visiting!