Upgrading hp a1477c and want to know.....

Hello, my Issue is i am upgrading my hp a1477c and need to know if the following parts are compatible and if they are good(feel free to advise me towards better parts). I am planning on buying a new Mobo because i want am3 support for a 550 phenom II x2(should i get 545)? Will buying a GIGABYTE GA-MA770T-UD3P AM3 AMD 770 ATX AMD Motherboard - Retail solve my woes? Is there any other things i should worry about. I am also buying 4gb (2x2) of ddr3 1600(g-skill) ram. I am just wondering if i need to buy any other things for these 4 new additions to work;

1.PNY XLR8 VCG98GTEE1XEB GeForce 9800 GT 1GB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready SLI Support Video Card - Retail

2.G.SKILL Ripjaws Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL7D-4GBRM - Retail

3.AMD Phenom II X2 550 Black Edition Callisto 3.1GHz Socket AM3 80W Dual-Core Processor Model HDZ550WFGIBOX - Retail

4.GIGABYTE GA-MA770T-UD3P AM3 AMD 770 ATX AMD Motherboard - Retail

Upon buying these items will all prerequisites be met for the processor and graphics card to work? Do i need to buy a new Power Supply? I am not very computer savvy. Please help me!


notes:the computer as is, only supports ddr1, socket is 939.

alex