I have 2 hard drives in my 3ghz 512 video memory and 1 ghz of RAM but my computer run slow do I need more RAM.:)

Well that would depend on what kind of OS you use, and what you have installed on your computer.
Windows XP should work fine with 1GB of memory, for Vista Basic I recommend a minimum of 1.5GB and Vista Premium 2GB or more. (Allways take Microsoft min and recommended requirement for memory, times 1.5/2)
Another reason could be installed fonts, if you use Graphic Programs like Corel or Adobe.
A lot of installed fonts will slow down a computer significantly. Another good thing to is change the location of the page file to the Hard drive that is not loading the OS. Check your taskmanager also for programs that start up on boot and remain in memory.