How to find what was installed recently

Hey guys,

I'm TOTALLY new to the mac so bear with me!

I THINK I might have over installed a program. I kept having problems getting it to fully install so I kept re-starting the installation. I noticed how much space I have now, and it looks to me as though it MIGHT have actually taken up more space than it should, had it been installed only once (I could be wrong though)

Is there a way to see the most recently installed programs? I want to make sure it doesn't say there's 5 copies of one program.

Also, while we're at it, is there a way to see a graphical view of what space is being used up on my hard drive, and what is using it?

Thanks so much!

--Electric