Hi could you please tell me if this build is compatible for computers?

Yeah they are compatible. Use the 64 bit version of Windows 7 if you want to fully utilize your 4GB of RAM. 32 bit OS will only be able to use about ~3.5GB even if you have 4GB or more installed. Also consider graphics card with gddr3 of memory even if just 512MB in size. All graphics cards with just ddr2 memory (no matter how large) are still slow and just good enough for casual gaming.