Something to add to this conversation, though Dirock's link pretty much showed it in spades..
A friend of mine and I built 2 identical computers (same motherboard, same RAM, same processor, etc) with the only differences being that he got an SSD and I have my old HDD from my previous computer (it's old and will probably die soon too. It's like 6 or 7 years old) and the video card (he has an ADI and I have a GeForce). The only differences we have in load times is when windows loads from a cold boot. His loads about 30seconds faster than mine. If I had a new HDD I'm pretty sure the load times would be much closer.