Hey ChaCha,
Remember, RAM is totally different from your Hard Drive. And RAM and Memory is the same thing. Memory or Ram is what your computer uses for 'holding things (thoughts, photos, graphics, programs) in the air, almost literally, holding them on or running. Your HD is simply where all the bulk of programs and files are held. (Non memory related basically).
So 1 Gig of Ram or Memory is totally different from your HD or Hard Drive.
Usually, with Windows, everyone now runs with 4 Gigs of Ram. If you have WinXP, you can only use 3 of those, so no matter what, XP will only have 3 Gigs to run with as it cant see any more. Win64, vista 64 (cough cough) and Win7 64 can run higher amounts of Ram (like an Apple, heh heh), but WinXP regular cannot.
Back to HD's. I had a 1TB installed in my Mac almost immediately. I then emailed Apple and told them that they should up their Macs to 1TB's as a standard and a short time later, they did, making 1TB's a standard you can get in your iMacs. (It didnt make sense that Apple have the most powerful iPod in the world, with 60 Gigs of HD space and their iMacs were only 360 Gigs.. So I told them that.. THey need to continue being the leaders in all fields, not just iPods.. ).