|It would be helpful to know which CPU you currently have. What is CPU: LGA 3*2?|
To be able to run Win7 on your system, all you'd have to do is add more RAM. Unfortunately, 2GB is the max for your board, but as Jolicloud said, that's good enough for Win7 32-bit. The 8400GS 256MB is not a gaming card but it's fine for general purpose use. The amount of video memory doesn't necessarily mean a card faster. Do you think an 8400GS 2GB would be faster than a 8400GS 256MB? High end cards benefit from large amounts of memory, but not low end cards. But a lot of manufacturers put 2GB on lower end cards to sucker people into to buying them. If you want a 2GB card, make sure it's capable of talking advantage of it. That means a reatively high end gaming card ($100+) & make sure you have a power supply that can handle it.