Best software for graphing

Okay, so I decided I wanted to try and create a series of graphs on my new mac!
What I want to do is be able to use a graph to represent my weight lifting gains

I want to be able to put in the weight lifted week by week
and I want it to be a series of graphs, that is, one for bench press, one for curls, one for squats, etc.

and I want each exercise to have two graphs, one depicting my gains, and one depicting my friend's


okay, I know that's a lot to ask, but what program would be best to use to accomplish this task? I kind of looked at that iWork thing Mark offered up but couldn't figure it out either way

and when I do find the best program, a quick little run-through on how I would make said graphs would be amazing

Have a look at Numbers in the iLife trial - that will do perfectly. Or look at NeoOffice's spreadsheet.

Numbers should be part of the iWorks package.

Dammit, you're right - iWork not iLife.

The spreadhseet in Neo-Office should be fine - or as the others have said, if you intend to get iWork, use numbers.